Greetings!
If one serving has 7.8 grams of fat in, then that means that 1 and a half servings will have 1 and a half times 7.8:
x 7.8 = 11.7 , so this means he has eated 11.7 grams of fat.
To find the remainder, simply minus 11.7 from 60:
60 = 11.7 = 48.3
So he can have 48.3 more grams of fat that day.
Hope this helps!