Question

~Please only answer if you know for sure~

At the start of the week, you could run for 8 minutes. By the end of the week, you could run for 15 minutes. Which proportion could you use to find the percent increase in your running time?

7/15=n/100

8/7=n/100

7/8=n/100

8/15=n/100

Answer 1

8/15

the change is tracked by tracing the second value from the first

8 being the first and 15 being the second.

the difference between the 2 should be the percent increase

8/15=....?

thats the proportion you use :)

Answer 2

So first of all, the percent increase formula is (new-original/original)*100
If you plug everything we have into the equation, it gives us:
(15-8)/8*100 = n
simplify and you get:
7/8*100 = n
divide both sides by 100 and you get your answer
which is:
7/8=n/100

Hope this helped!! :D