Question

Comprando 2 milk shakes e 1 bolo gastamos R$13,00. Comprando 1 milk shake e 2 bolos gastamos R$11,00. Quanto gastamos comprando 1 milk shake 1 bolo?

Answer 1

2m+b=13
m+2b=11 ×(-2)

2m+b=13
-2m-4b=-22

-3b=-9
b=-9/-3
b=3

m+2×3=11
m+6=11
m=11-6
m=5

m+b=?
5+3=8
Gastará 8 reais