Sagot :
n + 40 = 2(14 + n)
n + 40 = 28 + 2n
n = 2n + 28 - 40
n = 2n - 12
n - 2n = - 12
n - 2n = - 12
- n = - 12
n = 12.
n + 40 = 28 + 2n
n = 2n + 28 - 40
n = 2n - 12
n - 2n = - 12
n - 2n = - 12
- n = - 12
n = 12.