To solve this problem you must apply the proccedure shown below:
1- Let's give values to the weight of each fruit:
orange=0.5 kg
grapefruit=(0.5)+(0.08)(0.5 kg)=0.54 kg
apple=(0.5)-(0.1)(0.5 kg)=0.45 kg
2- Therefore, you have:
%=100%-(apple/grapefruit)x100
%=100%-(0.45/0.54)X100
%=16.66%
The answer is: 16.66%