X=Amount of skittles at the start.
Nasir ate 10 skittles and Seif ate 6 skittles so the number of skittles they had(x) - how many they both ate equals : 2/3;
(x-10)/(x-6)=2/3
3(x-10)=2(x-6)
3x-30=2x-12
x-30=-12
x=18
They each started with 18 skilttles.
The correct answer would be the last option, 6.6.