# How do you solve for b in d = 3a + 3b ?

Apr 23, 2018

$\implies b = \frac{d}{3} - a$

#### Explanation:

We are given

$d = 3 a + 3 b$

Subtract $3 a$ from both sides

$d - 3 a = 3 a + 3 b - 3 a$

$d - 3 a = \cancel{3 a} + 3 b \cancel{- 3 a}$

$d - 3 a = 3 b$

Divide both sides by $3$

$\frac{d - 3 a}{3} = \frac{3 b}{3}$

$\frac{d}{3} - \frac{\cancel{3} a}{\cancel{3}} = \frac{\cancel{3} b}{\cancel{3}}$

$\frac{d}{3} - a = b$