Solve for y 3x+7y=21

$3 x + 7 y = 21$

Step 1

Subtract $3 x$ from both sides of the equation.

$7 y = 21 - 3 x$

Step 2

Divide each term in $7 y = 21 - 3 x$ by $7$ and simplify.

Divide each term in $7 y = 21 - 3 x$ by $7$ .

$\frac{7 y}{7} = \frac{21}{7} + \frac{- 3 x}{7}$

Simplify the left side.

Cancel the common factor of $7$ .

Cancel the common factor.

$\frac{7 y}{7} = \frac{21}{7} + \frac{- 3 x}{7}$

Divide $y$ by $1$ .

$y = \frac{21}{7} + \frac{- 3 x}{7}$

Simplify the right side.

Simplify each term.

Divide $21$ by $7$ .

$y = 3 + \frac{- 3 x}{7}$

Move the negative in front of the fraction.

$y = 3 - \frac{3 x}{7}$