Question

Si a + b + c = 40, a - b = 20 y a - c = 30. Calcular "a"

Answer 1

a + b + c = 40

a - b = 20

a - 20 = b

a - c = 30

a - 30 = a

Reemplazamos en el primer dato

a + a - 20 + a - 30 = 40

3a - 50 = 40

3a = 90

a = 30