a) 1/5 + 3/5 = 4/5
b) 2/3 + 3/5 = 10/15 + 9/15 = 19/15 = 14/15
c) 3/7 + 2/9 = 27/63 + 14/63 = 41/63
d) 3/4 - 1/4 = 2/4
e) 3/8 - 2/3 = 9/24 - 16/24 = -7/24
f) 1/5 - 3/13 = 13/65 - 15/65 = -2/65
g) 5/6 + 5/8 = 40/48 + 30/48 = 70/48 = 1 22/48 = 1 11/24
h) 3/10 - 17/35 = 105/350 - 170/350 = -65/350 = -13/70