Answer:
11/24
Step-by-step explanation:
Since all the denominators are different, you will have to find a number that they are all factors of to find the answer. To find the missing fractions, all denominators should be the same. We know 6*4=24, and 8*3=24, so 24 is the chosen denominator.
1/6 -> 4/24 (to get this, times both parts by 4)
1/8 -> 3/24 (times both parts by 3)
1/4 -> 6/24 (times both parts by 6)
Add all fractions together and you get 13/24.
24/24 - 13/24 = 11/24, so the remaining fraction is 11/24 since you can't simplify it further.
Sorry if this doesn't help much, my math may be a bit fuzzy ^^'