Question

Qual o valor de x?

A + b = 19
A - b = 3
A x b = x ?​

Answer 1

A + b = 19
A = 19 - b (I)

A - b = 3
A = 3 + b (II)

Agora igualamos os valores de A:
19 - b = 3 + b .: 2b = 16 .: b = 8

A = 3 + b .: A = 3 + 8 = 11

A x b = 8 x 11 = 88