For number 1a. the answer is 7 to 26 or
7:26 or

For number 2a. the answer is 8 to 28 or
8:28 or

For number 3a. the answer is 12 to 13 or
12:13 or

For number 4a. the answer is 19 to 12 or
19:12 or

For number 5a. the answer is 29 to 10 or
29:10 or

For number 6a. the answer is 11 to 28 or
11:28 or

I just did your homework
Y=ab^x
logab=x
log7(1/343)=-3
y=7(1/343)^-3
The answer would be “-876”