Six times the sum of a number and twelve is forty.

X-the number

6 (x + 12) = 40 |use distributive property: a (b + c) = ab + ac

6x + 72 = 40 |subtract 72 from both sides

6x = - 32 |divide both sides by 6

x = - 32/6

x = - 16/3

x = - 5 1/3