Pre-Algebra Examples

3 x + 4 y = 12

$3 x + 4 y = 12$

Step 1

Solve for

y

$y$ .

Tap for more steps...

Step 1.1

Subtract

3 x

$3 x$ from both sides of the equation.

4 y = 12 - 3 x

$4 y = 12 - 3 x$

Step 1.2

Divide each term in

4 y = 12 - 3 x

$4 y = 12 - 3 x$ by

4

$4$ and simplify.

Tap for more steps...

Step 1.2.1

Divide each term in

4 y = 12 - 3 x

$4 y = 12 - 3 x$ by

4

$4$ .

\frac{4 y}{4} = \frac{12}{4} + \frac{- 3 x}{4}

$\frac{4 y}{4} = \frac{12}{4} + \frac{- 3 x}{4}$

Step 1.2.2

Simplify the left side.

Tap for more steps...

Step 1.2.2.1

Cancel the common factor of

4

$4$ .

Tap for more steps...

Step 1.2.2.1.1

Cancel the common factor.

\frac{4 y}{4} = \frac{12}{4} + \frac{- 3 x}{4}

$\frac{4 y}{4} = \frac{12}{4} + \frac{- 3 x}{4}$

Step 1.2.2.1.2

Divide

y

$y$ by

1

$1$ .

y = \frac{12}{4} + \frac{- 3 x}{4}

$y = \frac{12}{4} + \frac{- 3 x}{4}$

y = \frac{12}{4} + \frac{- 3 x}{4}

$y = \frac{12}{4} + \frac{- 3 x}{4}$

y = \frac{12}{4} + \frac{- 3 x}{4}

$y = \frac{12}{4} + \frac{- 3 x}{4}$

Step 1.2.3

Simplify the right side.

Tap for more steps...

Step 1.2.3.1

Simplify each term.

Tap for more steps...

Step 1.2.3.1.1

Divide

12

$12$ by

4

$4$ .

y = 3 + \frac{- 3 x}{4}

$y = 3 + \frac{- 3 x}{4}$

Step 1.2.3.1.2

Move the negative in front of the fraction.

y = 3 - \frac{3 x}{4}

$y = 3 - \frac{3 x}{4}$

y = 3 - \frac{3 x}{4}

$y = 3 - \frac{3 x}{4}$

y = 3 - \frac{3 x}{4}

$y = 3 - \frac{3 x}{4}$

y = 3 - \frac{3 x}{4}

$y = 3 - \frac{3 x}{4}$

y = 3 - \frac{3 x}{4}

$y = 3 - \frac{3 x}{4}$

Step 2

Rewrite in slope-intercept form.

Tap for more steps...

Step 2.1

The slope-intercept form is

y = m x + b

$y = m x + b$ , where

m

$m$ is the slope and

b

$b$ is the y-intercept.

y = m x + b

$y = m x + b$

Step 2.2

Reorder

3

$3$ and

- \frac{3 x}{4}

$- \frac{3 x}{4}$ .

y = - \frac{3 x}{4} + 3

$y = - \frac{3 x}{4} + 3$

Step 2.3

Write in

y = m x + b

$y = m x + b$ form.

Tap for more steps...

Step 2.3.1

Reorder terms.

y = - (\frac{3}{4} x) + 3

$y = - (\frac{3}{4} x) + 3$

Step 2.3.2

Remove parentheses.

y = - \frac{3}{4} x + 3

$y = - \frac{3}{4} x + 3$

y = - \frac{3}{4} x + 3

$y = - \frac{3}{4} x + 3$

y = - \frac{3}{4} x + 3

$y = - \frac{3}{4} x + 3$

Step 3

Use the slope-intercept form to find the slope and y-intercept.

Tap for more steps...

Step 3.1

Find the values of

m

$m$ and

b

$b$ using the form

y = m x + b

$y = m x + b$ .

m = - \frac{3}{4}

$m = - \frac{3}{4}$

b = 3

$b = 3$

Step 3.2

The slope of the line is the value of

m

$m$ , and the y-intercept is the value of

b

$b$ .

Slope:

- \frac{3}{4}

$- \frac{3}{4}$

y-intercept:

(0, 3)

$(0, 3)$

Slope:

- \frac{3}{4}

$- \frac{3}{4}$

y-intercept:

(0, 3)

$(0, 3)$

Step 4

Any line can be graphed using two points. Select two

x

$x$ values, and plug them into the equation to find the corresponding

y

$y$ values.

Tap for more steps...

Step 4.1

Write in

y = m x + b

$y = m x + b$ form.

Tap for more steps...

Step 4.1.1

Reorder

3

$3$ and

- \frac{3 x}{4}

$- \frac{3 x}{4}$ .

y = - \frac{3 x}{4} + 3

$y = - \frac{3 x}{4} + 3$

Step 4.1.2

Reorder terms.

y = - (\frac{3}{4} x) + 3

$y = - (\frac{3}{4} x) + 3$

Step 4.1.3

Remove parentheses.

y = - \frac{3}{4} x + 3

$y = - \frac{3}{4} x + 3$

y = - \frac{3}{4} x + 3

$y = - \frac{3}{4} x + 3$

Step 4.2

Create a table of the

x

$x$ and

y

$y$ values.

\begin{array}{c} x & y \\ 0 & 3 \\ 4 & 0 \end{array}

$\begin{array}{c} x & y \\ 0 & 3 \\ 4 & 0 \end{array}$

\begin{array}{c} x & y \\ 0 & 3 \\ 4 & 0 \end{array}

$\begin{array}{c} x & y \\ 0 & 3 \\ 4 & 0 \end{array}$

Step 5

Graph the line using the slope and the y-intercept, or the points.

Slope:

- \frac{3}{4}

$- \frac{3}{4}$

y-intercept:

(0, 3)

$(0, 3)$

\begin{array}{c} x & y \\ 0 & 3 \\ 4 & 0 \end{array}

$\begin{array}{c} x & y \\ 0 & 3 \\ 4 & 0 \end{array}$

Step 6