Respostas

2014-04-21T14:54:27-03:00
Só fazer o inverso

(-5) + 21 = 16
16 * 2 = 32
2014-04-21T15:17:36-03:00
X/2 - 21 = - 5

X/2 = -5 + 21

X/2 = 16

X= 16 x 2

X = 32