# How do you solve 7/9=b/(b-10)?

Jul 10, 2016

$\frac{7}{9} = \frac{b}{b - 10}$

By cross-multiplying, namely

$7 \cdot \left(b - 10\right)$ and $9 \cdot \left(b\right)$, we get

$7 b - 70 = 9 b$

Subtracting $7 b$ from both sides yields

$- 70 = 2 b$, and dividing both sides by $2$ yields

$b = - 35$