That's a 33% increase.
I calculated this using the formula:
Where n = the new value (16 in your question), o = the old value (12 in your question) and the result is outputted as a percent increase. You can check that this is correct by finding 33% of 12, adding the result to 12, and checking that the result equals your "new" number.
Note that 33% is only an approximation as your question requires a number rounded to the nearest whole.
The answer is 2 cubed so B
1 1/2 divided by 1 1/6 equals 1.28571429
Rounded: 1.28, 1.29, or 1.30 (depends on what they ask for)
3/4 divided by 1 3/8 equals 0.54545455
Rounded: 0.54 or 0.55
76766 is the correct answer