100%-15%=85% -- 0.85
A. doesn't work because it is increasing
B. works because your finding 85 percent since you decrease by 15 percent
C. doesn't work because you are not taking 15 percent from value of t
D. doesn't work because finging 15 percent of t and them subtracting from one won't give you the right answer
E.doesnt work because all you have to do is find 85 percent not subtract that from the original value
F.works because subtracting 15 percent from one and multiply by t would give the equation from B
So the answers are B and F