Answer:
360
Step-by-step explanation:
First time = 7:12
second time = 7:40
40 - 12 = 28
28 minutes have past
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.
1/4 is equivalent to 5/20
A number that is less that 7.5 can be used as the lesser of the two consecutive integers with the sum greater than 16, but only if the number used was added with one.