Answer :

68.75

what you would do is take the numerator divided by the denominator then multiply it by 100

from 70 g, mass of 48 g is fat. The percentage value is the value of a fraction of 100. 
percentage of fat can be calculated using the following formula
percentage of fat = mass of fat / total mass x 100 %
percentage = 48 g / 70 g x 100 % 
                   = 68.6 %
this is interpreted as,  68.6 % of the total mass is fat.