18. C
36-1=3y+1
3y=3y+2
y=y+2
No Solutions.
19. D
No matter what d is equal to, the answer on both sides will always be the same.
20.
a. 2n-1=37
2n=38
n=19
whole number
b. 2n+1=18
2n=17
n=17/2
not a whole number
c. 3n+5=n+7
2n+5=7
2n=2
n=1
whole number
d. n^2 +2=1
n^2=-1
n=i
no solution
Hope this helps.
