1. (3/4+1/20)×1/2=2/5

1) 3/4+1/20= 15+1 = 16/20=4/5

20

2) 4/5×1/2=4×1 = 2/5

5×2

2.(7/12-1/3)×16/19=4/19

1) 7/12-1/3=7-4 = 3/12=1/4

12

2) 1/4×16/19=1×16 = 4/19

4×19

3. (7 3/5-2 4/15)×9/32=1 1/2

1) 7 3/5-2 4/15=38/5-34/15=114-34 = 80/15= 16/3

15

2) 16/3×9/32=16×9 = 3/2= 1 1/2

3×32

4. (11/24+1/6)×1 3/5= 1

1) 11/24+1/6=11+4 = 15/24=5/8

24

2) 5/8×1 3/5= 5/8×8/5= 1