Question

calcular a equação 2x + 5y =150
x + y = 45

Answer 1

x+y=45
x=45-y

2x + 5y =150
2.(45-y)+5y=150
90-2y+5y=150
-2y+5y=150-90
3y=60
y=60/3
y=20

x=45-y
x=45-20
x=25