# How do you solve the proportion (x+1)/(x +3) = 15/21 ?

Apr 29, 2015

$x = 4$

Solution

$\frac{x + 1}{x + 3} = \frac{15}{21}$

$\left(x + 1\right) \left(21\right) = 15 \left(x + 3\right)$

$21 x + 21 = 15 x + 45$

$21 x - 15 x = 45 - 21$

$6 x = 24$

$x = \frac{24}{6}$

$x = 4$