So the problem is to find out how much is 68 in percent if 60 is the 100%, we can use a rule of three, simple, direct proportion to do it:
60 -------> 100%
68 --------> x
x = (68)(100)/60
x = 113.3
therefore 68 is the 113.3% of 60, which means that the error is of:
113.3 - 100 = 13.3%
