Решить пример а,б (по действиям)

а) ( 2/15 + 1 7/12 ) × 30/103 - 2 ÷ 2 1/4 × 9/32 + 2 1/3;

решаем по действиям:

1) 2/15 + 1 7/12 = 1 24/180 + 105/180 = 1 129/180 = 1 43/60;

2) 2 ÷ 2 1/4 = 2/1 × 4/9 = 8/9;

3) 1 43/60 × 30/103 = 103/60 × 30/103 = 1/2;

4) 8/9 × 9/32 = 1/4;

5) 1/2 - 1/4 = 2/4 - 1/4 = 1/4;

6) 1/4 + 2 1/3 = 2 + 1/4 + 1/3 = 2 + 3/12 + 4/12 = 2 + 7/12 = 2 7/12

ответ: 2 7/12.

б) ( 7 /1/2× 2 2/3 - 12 1/4 ÷ 7/9 ) ÷ 6 + 3 1/8 + 5 2/7;

решаем по действиям:

1) 7 1/2 × 2 2/3 = 15/2 × 8/3 = 120/6 = 20;

2) 12 1/4 ÷ 7/9 = 49/4 ÷ 7/9 = 49/4 × 9/7 = 63/4 = 15 3/4 ;

3) 20 - 15 3/4 = 20 - 15 - 3/4 = 5 - 3/4 = 5×4 / 4 - 3/4 = 20/4 - 3/4 = 17/4 = 4 1/4;

4) 4 1/4 ÷ 6 = 17/4 ÷ 6/1 = 17/4 × 1/6 = 17/24;

5) 17/24 + 3 1/8 = 3 + 17/24 + 3/24 = 2 + 20/24 = 3 20/24 = 3 5/6;

6) 3 5/6 + 5 2/7 = 8 + 35/42 + 12/42 = 8 + 47/12 = 9 5/42;

ответы : а) 2 7/12; б) 9 5/42.