Let's just start wth number 7, yours isn't right.
So 20 is 4% of a number (call it x). So the equation for a problem like this is:
(The number) = (the percent%) x (x, the unknown)
So 20 = 4%of x
20=.04x
Isolate the x by dividing both sides by the decimal version of the percent (above, 0.04)
20/0.04 = 0.04x / 0.04
20/0.04 = x
X = 500
Do the same thing on all of the problems
