The radius of a circle with a circumstance of 10 feet

You could change all fractions to decimals
2 5/8 = 2.625
3/4 = 0.75
2.625 - 0.75 = 1.875

If you need to stay in fractions, you could do it this way.
2 5/8 = 21/8
3/4 = 6/8

21/8 - 6/8 = 15/8 = 1 7/8 Her classmates ate 1 7/8 pounds of nuts

If your calculator has an (a b/c) key the whole problem can be done on your calculator