for the first one it is the second option because of one property of logarithms:
log(a)-log(b)=log
for the second one using the same property we can say that we third option is correct and not the second one but we use one more property of the logarithm
loga(b)^x=xloga(b) the power of the logarithm becomes a fator and
is equal to 
Zeros do not count as a sigfig so when you do something like this problem just include the numbers until you hit your significant figure limit and then substitute zeros where you can. 20000
I think it's 182 I'm not completely sure though
Answer:
x=9
Step-by-step explanation:
6+5x=51
-6 -6
________
0 5x=45
_ _
5 5
x=9