Ithought this was much more easier for you! : )

Problem 1)

The base of the exponential is 12 which is also the base of the log as well. The only answer choice that has this is choice B.


Problem 2)

log(x) + log(y) - 2log(z)
log(x) + log(y) - log(z^2)
log(x*y) - log(z^2)
log[(x*y)/(z^2)]

Answer is choice D


Problem 3)

log[21/(x^2)]
log(21) - log(x^2)
log(21) - 2*log(x)

This matches with choice B


Problem 4)

Ln(63) = Ln(z) + Ln(7)
Ln(63)-Ln(7) = Ln(z)
Ln(63/7) = Ln(z)
Ln(9) = Ln(z)
z = 9


Problem 5)

Ln(5x-3) = 2
5x-3 = e^2
5x = e^2+3
x = (e^2+3)/5

This means choice A is the answer