Question

a+B =287 iar A= B/4 +12

Answer 1

a + b = 287

a = b / 4 + 12

( b / 4 + 12 ) + b = 287

b / 4 + b = 287 - 12

b + 4 b = 4 × 275

5 × b = 1 100

b = 1 100 : 5

b = 220

a = 287 - 220 ⇒   a = 67

Answer 2

$\frac{b}{4} + 12 + b = 287 \\ \frac{b}{4} + \frac{48}{4} + \frac{4b}{4} = \frac{1148}{4} \\ b + 48 + 4b = 1148 \\ 5b + 48 = 1148 \\ 5b = 1100 \\ b = 220$
a=287-220
a=67