First you have make the 2 and a half into 5/2. Then you have to find a common denominator of the two fractions, which would be 8. So the 7/8 you dont need to do anything to but the 5/2 you do... so multiply both the top and the bottom by 4 so you can get 8 on the bottom. that would be 20/8. now you can add them. so 7/8 + 20/8 = 27/8
