(3/4- 8 1/4) ÷ 3 1/2 (-1 7/8+3 1/8) ÷1 3/7 - = (-4 2/3+5) ÷ 10 (-1 3/8 +2) ÷ 3 1/8

3/4-1/2+7/8=9/8
1) 3/4-1/2=3/4-2/4=1/4
2) 1/4+7/8=2/8+7/8=9/8

5/6-2/3+1/4=10/24
1)  5/6-2/3=5/6-4/6=1/6
2)  1/6+1/4=4/24+6/24=10/24

1/3-(1/9+1/6)=1/18
1)  1/9+1/6=6/54+9/54=15/54=5/18
2)  1/3-5/18=1/18

(3/4 - 8 1/4) ÷ 3 1/2        (-1 7/8 + 3 1/8) ÷ 1 3/7
 --       = - 68 37/56,
(-4 2/3 + 5) ÷ 10             (-1 3/8 + 2) ÷ 3 1/8

1) 3/4 - 8 1/4 = 3/4 - 33/4 = - 30/4 = - 7 2/4 = - 7 1/2,
2) -7 1/2 ÷ 3 1/2 = -15/2 ÷ 7/2 = - 15/2 * 2/7 = - 15/7 = - 2 1/7,
3) -4 2/3 + 5 = 1/3,
4) 1/3 ÷ 10 = 1/3 * 1/10 = 1/30,
5) -2 1/7 ÷ 1/30 = -15/7 ÷ 1/30 = -15/7 * 30/1 = -450/7 = -64 2/7,

6) -1 7/8 + 3 1/8 = -15/8 + 25/8 = 10/8 = 1 2/8 = 1 1/4,
7) 1 1/4 ÷ 1 3/7 = 5/4 ÷ 10/7 = 5/4 * 7/10 = 7/8,
8) -1 3/8 + 2 = 5/8,
9) 5/8 ÷ 3 1/8 = 5/8  ÷ 25/8 = 5/8 * 8/25 = 1/5,
10) 7/8 ÷ 1/5 =7/8 * 5/1 = 35/8 = 4 3/8,

11) -64 2/7 - 4 3/8 = - (64 2/7 + 4 3/8) = - (68 + 16/56 + 21/56) = - 68 37/56