# Deers and roes live in the forest. Deers make up 30% of the forest life. There are 144 deers less than roes. How many roes live in the forest? Answer: 252 roes. How do I solve this problem?

Mar 10, 2016

Convert the problem into equations that can be solved for the number of roe.

#### Explanation:

If $x$ is the number of roes, then the number of deer is $x - 144$

If $T$ is the total, then deer are $0.3 \cdot T$

$x + \left(x - 144\right) = T$
$2 x = T + 144$

$x - 144 = 0.3 \cdot T$
$x = \frac{3 T}{10} + 144$

Substituting, $2 \left(\frac{3 T}{10} + 144\right) = T + 144$
$\frac{3 T}{5} - T = 144 - 288$
$2 T = 144 \cdot 5 = 720$

$T = 360$

$x = 108 + 144 = 252$