First problem:

8^(x+2)=(1/2)^(x-11)

log(8^(x+2)) = log((1/2)^(x-11))
(x+2)log(8) = (x-11)log(1/2)
(x+2)(.903) = (x-11)(-.301)
.903x + 1.806 = -.301x + 3.311
1.204x = 1.505

x = 1.25 or 5/4

I don't have the time or desire to do the others, but if you can follow what I did, you should be able to get them. Basically you just need to know that

log(a^b) = (b)log(a)