Вычислите значение у по формуле а=86-5b, если: 1)b=17; 2)b=9 !

а=86-5b,если:1)b=17;2)b=9

а=86-5b=86-5*17=86-85=1
а=86-5b=86-5*9=86-45=41

А=86-5*17
а=86-85=1
а=86-5*9
а=86-45=41

(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

(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