I think it's D but I'm not %100 sure
#13 would be 100%.
#15 would be $9.90.
#17 would be 408.
#19 would be 27840.
#21 would be 26.
Sorry for the late reply.
The answer is 3. 4 because 4 doesn’t have a variable :)
Before you start working on this problem, make sure you know
how to use a couple of the tools in your toolbox:
Tool #1: 37-1/2 percent means 0.375
Tool #2: In math problems, "of" almost always means "times".
====================================
Your question says
"37-1/2 percent of blank is 36".
Translate it with your tools:
0.375 times blank = 36 .
Divide each side by 0.375: Blank = 36 / 0.375 .
Now grab your pencil or your calculator, and find the value of that
fraction (do the division). Blank is equal to the value of the fraction.
To check your answer (find out whether it's correct):
Do exactly what the question says.
Multiply (0.375) times (your answer). If you get 36,
then your answer is correct. If not, it's not.
For multiplication, if both integers have like signs, it is always positive. If they have unlike signs it is negative.
For division, if both integers have like signs it is positive. If they have unlike signs it is negative.