we have
1 3/8=1+3/8=11/8
1/3+11/8
Find equivalent fractions
multiply 1/3 by 8/8 ------> 8/24
multiply 11/8 by 3/3 -----> 33/24
so
8/24+33/24=41/24
Convert to mixed number
41/24=24/24=17/24=1 17/24
2 4/5=2+4/5=14/5
14/5-1/3
Find equivalent fractions
multiply 1/3 by 5/5 -----> 5/15
multiply 14/5 by 3/3 ----> 42/15
so
42/15-5/15=37/15
convert to mixed number
37/15=30/15+7/15=2+7/15=2 7/15