Question

the sum of twelve and a number is no greater than the sum of twice the number and -8

Answer 1

the sum of 12 and a number
(12 + n)

is no greater
< = 

then the sum of twice the number and 8
(2n +(-8)) = (2n - 8)

so we have :
(12 + n) < = (2n - 8)