Bantu buat yg bida pke cara

Bantu buat yg bida pke cara

$frac{8}{20 } = frac{10}{10 + a}$
$frac{2}{5 } = frac{10}{10 + a}$
$20 + 2a = 50$
$2a = 30$

$a= 15$
b.
$frac{8}{20} = frac{4}{b}$
$frac{2}{5 } = frac{4}{b}$
$2b = 20$
$b = 10$
jadi
$a + b = 15 + 10 \ = 25$