Question

x+y=90 qual o valor de y​

Answer 1

Resposta:

$\left \{ {{x+y=90} \atop {30y-45x=0}} \right.$

x = 90 - y

30y - 45(90 - y) = 0

30y - 4050 + 45y = 0

75y = 4050

y = 4050/75

y = 54