Three and seven eighth minus one and one half

3 7/8-1 1/2  change mixed numbers to improper fractions

rule a b/c=(ac+b)/c

31/8-3/2  make a common denominator of 8

31/8-(3/2)(4/4)

31/8-12/8

(31-12)/8

19/8  convert back to a mixed number

(16+3)/8

2+3/8

2 3/8

I know that there is easier ways to do this but this is the way to do it when it isn't an easy problem :P