The easiest way to figure out a simpler math problem like this is to look at all of the answers.
Look at all of the answers and see which one times 2 is 5 less than 90.
A.) 85.00 ----> 85 x 2 = 170 (Nope)
B.) 42.50 ----> 42.50 x 2 = 85 (Yep)
C.) 50.50 ----> 50.50 x 2 = 101 (Nope)
D.) 47.50 ----> 47.50 x 2 = 95 (Nope)
That means the correct answer is $42.50
Hope this helps!