Question

4x + 2y =48 sendo x=3 ? 

Answer 1

$4x + 2y =48$

Sendo x = 3, basta substituir o valor de x

$4*3 + 2y =48 \\ \\ 12 + 2y = 48 \\ \\ 2y = 48 - 12 \\ \\ 2y = 36 \\ \\ y = \dfrac{36}{2} \\ \\ y = 18$

Answer 2

4x + 2y = 48   sendo x = 3

4(3) +  2y = 48

12 + 2y = 48

2y = 48 - 12

2y = 36

y = $\frac{36}{2}$

y = 18