1、
4/9 X [ 3/4 - (7/16 - 4/16)]
=4/9 X [12/16 - 3/16]
=4/9 X 9/16 = 1/4
2、
(3/4-3/5×5/6)÷(5/8+1/3)
=(3/4 - 3/6) ÷ (15/24 + 8/24)
=(3/4 - 2/4) ÷ 23/24
=1/4 X 24/23
=6/23
3、
1/2 ÷ 15 X 5/6 ÷ 3/4
=1/2 X 1/15 X 5/6 X 4/3
=1/27
4、
[1-（1/12+1/24）×6]÷1/24
= [ 1 - 3/24 X 6 ] X 24
=24 - 3X6
=24-18
=6
5、
4/9 ÷ [4/5 - (1/5 + 1/3)]
=4/9 ÷ [4/5 - 1/5 - 1/3]
=4/9 ÷ [3/5 - 1/3]
=4/9 ÷ 4/15
=4/9 X 15/4
=5/3
6、
7.8÷[3.2×（1-5/8）+3.6]
=39/5 ÷ [16/5 X 3/8 + 18/5]
=39/5 ÷ [6/5 + 18/5]
=39/5 ÷ 24/5
=39/24
=13/8
7、
2/3 - 3/4 X 4/11+ 1/3 ÷3/7
=2/3 - 3/11 + 7/9
=66/99 - 27/11 + 77/99
=116/99
8、
8/9 ÷ [(2/5 + 1/10) X 4/3]
=8/9 ÷ [5/10 X 4/3]
=8/9 ÷ 2/3
=8/9 x 3/2
=4/3
9、
18 X 0.25 + 12 X 1/4 + 2.5
=(18+12) X 1/4 + 2.5
=30/4 + 10/4
=40/4
=10
10、
[1/2 - (3/4 - 3/5)] ÷ 7/10
=[10/20 - 3/20] X 10/7
=7/20 X 10/7
=1/2
11、
5 ÷ 5/7 - 5/7 X 15
= 5 X 7/5 - 5X15 / 7
= 7 - 75/7
= -26/7
12、
3/4 X 6/7 + (1 - 3/4) X 6/7
=(3/4 + 1 - 3/4) X 6/7
=1 X 6/7
=6/7
13、
1/3 X 1/2 + 5/4 X 2/5
=1/6 + 1/2
=2/3