The answer is 30%.
This is because 60-42 is 18.
Now our new problem is what percent of 60 is 18?
x=18%.
Now we have two simple equations:
1) 60=100%
2) x=18%
Where left sides of both of them have the same units, and both right sides have the same units, so we can do something like that:
60/x=100%/18%
x=18%
Hope this helps!!
