Basic Math Examples

$\frac{7}{15 z} - \frac{1}{5} = 4$

Step 1

Move all terms not containing $z$ to the right side of the equation.

Tap for more steps...

Step 1.1

Add $\frac{1}{5}$ to both sides of the equation.

$\frac{7}{15 z} = 4 + \frac{1}{5}$

Step 1.2

To write $4$ as a fraction with a common denominator, multiply by $\frac{5}{5}$ .

$\frac{7}{15 z} = 4 \cdot \frac{5}{5} + \frac{1}{5}$

Step 1.3

Combine $4$ and $\frac{5}{5}$ .

$\frac{7}{15 z} = \frac{4 \cdot 5}{5} + \frac{1}{5}$

Step 1.4

Combine the numerators over the common denominator.

$\frac{7}{15 z} = \frac{4 \cdot 5 + 1}{5}$

Step 1.5

Simplify the numerator.

Tap for more steps...

Step 1.5.1

Multiply $4$ by $5$ .

$\frac{7}{15 z} = \frac{20 + 1}{5}$

Step 1.5.2

Add $20$ and $1$ .

$\frac{7}{15 z} = \frac{21}{5}$

Step 2

Find the LCD of the terms in the equation.

Tap for more steps...

Step 2.1

Finding the LCD of a list of values is the same as finding the LCM of the denominators of those values.

$15 z, 5$

Step 2.2

Since $15 z, 5$ contains both numbers and variables, there are two steps to find the LCM. Find LCM for the numeric part $15, 5$ then find LCM for the variable part $z^{1}$ .

Step 2.3

The LCM is the smallest positive number that all of the numbers divide into evenly.

1. List the prime factors of each number.

2. Multiply each factor the greatest number of times it occurs in either number.

Step 2.4

$15$ has factors of $3$ and $5$ .

$3 \cdot 5$

Step 2.5

Since $5$ has no factors besides $1$ and $5$ .

$5$ is a prime number

Step 2.6

The LCM of $15, 5$ is the result of multiplying all prime factors the greatest number of times they occur in either number.

$3 \cdot 5$

Step 2.7

Multiply $3$ by $5$ .

$15$

Step 2.8

The factor for $z^{1}$ is $z$ itself.

$z^{1} = z$

$z$ occurs $1$ time.

Step 2.9

The LCM of $z^{1}$ is the result of multiplying all prime factors the greatest number of times they occur in either term.

$z$

Step 2.10

The LCM for $15 z, 5$ is the numeric part $15$ multiplied by the variable part.

$15 z$

Step 3

Multiply each term in $\frac{7}{15 z} = \frac{21}{5}$ by $15 z$ to eliminate the fractions.

Tap for more steps...

Step 3.1

Multiply each term in $\frac{7}{15 z} = \frac{21}{5}$ by $15 z$ .

$\frac{7}{15 z} (15 z) = \frac{21}{5} (15 z)$

Step 3.2

Simplify the left side.

Tap for more steps...

Step 3.2.1

Rewrite using the commutative property of multiplication.

$15 \frac{7}{15 z} z = \frac{21}{5} (15 z)$

Step 3.2.2

Cancel the common factor of $15$ .

Tap for more steps...

Step 3.2.2.1

Factor $15$ out of $15 z$ .

$15 \frac{7}{15 (z)} z = \frac{21}{5} (15 z)$

Step 3.2.2.2

Cancel the common factor.

$15 \frac{7}{15 z} z = \frac{21}{5} (15 z)$

Step 3.2.2.3

Rewrite the expression.

$\frac{7}{z} z = \frac{21}{5} (15 z)$

Step 3.2.3

Cancel the common factor of $z$ .

Tap for more steps...

Step 3.2.3.1

Cancel the common factor.

$\frac{7}{z} z = \frac{21}{5} (15 z)$

Step 3.2.3.2

Rewrite the expression.

$7 = \frac{21}{5} (15 z)$

Step 3.3

Simplify the right side.

Tap for more steps...

Step 3.3.1

Cancel the common factor of $5$ .

Tap for more steps...

Step 3.3.1.1

Factor $5$ out of $15 z$ .

$7 = \frac{21}{5} (5 (3 z))$

Step 3.3.1.2

Cancel the common factor.

$7 = \frac{21}{5} (5 (3 z))$

Step 3.3.1.3

Rewrite the expression.

$7 = 21 (3 z)$

Step 3.3.2

Multiply $3$ by $21$ .

$7 = 63 z$

Step 4

Solve the equation.

Tap for more steps...

Step 4.1

Rewrite the equation as $63 z = 7$ .

$63 z = 7$

Step 4.2

Divide each term in $63 z = 7$ by $63$ and simplify.

Tap for more steps...

Step 4.2.1

Divide each term in $63 z = 7$ by $63$ .

$\frac{63 z}{63} = \frac{7}{63}$

Step 4.2.2

Simplify the left side.

Tap for more steps...

Step 4.2.2.1

Cancel the common factor of $63$ .

Tap for more steps...

Step 4.2.2.1.1

Cancel the common factor.

$\frac{63 z}{63} = \frac{7}{63}$

Step 4.2.2.1.2

Divide $z$ by $1$ .

$z = \frac{7}{63}$

Step 4.2.3

Simplify the right side.

Tap for more steps...

Step 4.2.3.1

Cancel the common factor of $7$ and $63$ .

Tap for more steps...

Step 4.2.3.1.1

Factor $7$ out of $7$ .

$z = \frac{7 (1)}{63}$

Step 4.2.3.1.2

Cancel the common factors.

Tap for more steps...

Step 4.2.3.1.2.1

Factor $7$ out of $63$ .

$z = \frac{7 \cdot 1}{7 \cdot 9}$

Step 4.2.3.1.2.2

Cancel the common factor.

$z = \frac{7 \cdot 1}{7 \cdot 9}$

Step 4.2.3.1.2.3

Rewrite the expression.

$z = \frac{1}{9}$

Step 5

The result can be shown in multiple forms.

Exact Form:

$z = \frac{1}{9}$

Decimal Form:

$z = 0.\overline{1}$