Twelve less than a number, x.
12-x
x-12
12+x
x+12
d decreased by 17 is 5.
d+17=5
d=17-5
17-d=5
d-17=5
The product of n and 8 is 24.
8/n=24
n/8=24
8n=24
n+8=24
The quotient of 40 and n.
40/n
n/40
40-n
n-40
The sum of 6 and 3 times a number, n.
6+3n
6+3+n
6-3n
3+6n