a) 2/5 + 3/10 = 4/10 + 3/10 = 7/10
b) 7/8 + 5/12 = 21/24 + 10/24 = 31/24
c) 4/7 + 7/9 = 36/63 + 49/63 = 85/63
d) 3/8 + 5/6 = 9/24 + 20/24 = 29/24
a) 2/5 + 3/10 = 4/10 + 3/10 = 7/10
b) 7/8 + 5/12 = 21/24 + 10/24 = 31/24
c) 4/7 + 7/9 = 36/63 + 49/63 = 85/63
d) 3/8 + 5/6 = 9/24 + 20/24 = 29/24