Question

Sonia e Graça pesam ,juntas ,145kg. Graça pesa 2/3 do peso de sonia.quanto pesa cada uma?

Answer 1

$\left\{\begin{array}{ccc}S + G = 145\\\\G = \frac{2}{3}S \end{array}\right\to \left\{\begin{array}{ccc}G = 145-S\\\\145-S = \frac{2}{3}S \end{array}\right$



$Resolu\c{c}\~ao\to \left\{\begin{array}{ccc}145-S = \frac{2}{3}S\\\\435-3S = 2S\\\\5S = 435\\\\\boxed{S = 87kg}\\\\\boxed{G = 145-87 = 58kg}\end{array}\right$

Sônia pesa 87kg e Graça 58kg.

Espero ter ajudado. :))