Question

a/b = 2/3 a-b = 30
a=? b=?

Answer 1

a/b = 2/3 ==> a = 2b/3
a - b = 30
2b/3 - b = 30 |×3
2b - 3b = 90
b = - 90
a = 30 - 90 = - 60

Answer 2

$\frac{a}{b}=\frac{2}{3} \\ \\ a=\frac{2b}{3}$
Inlocuim in scadere
$a-b=30 \\ \\ \frac{2b}{3}-b=30 \\ \\ \frac{2b}{3}-\frac{3b}{3}=30 \\ \\ \frac{(-1)\cdot b}{3}=30 \\ \\ (-1)\cdot b=90 \\ \\ b=90:(-1) \\ \\ b=-90 \\ \\ a=30+(-90) \\ \\ a=-60$