Answer:
Step-by-step explanation:
the second one , why? because 7a-12a=-5a
4 - 8 = -4
Step-by-step explanation:

all the details are in the attachment.
Answer:
If A is wrong then B I think
Step-by-step explanation:
Replace x with y and solve for y~
y=2*
x=2^y
log x = y log 2
y=log x / log 2
Hope this helps and leave a brainliest to help me reach expert ;)