Вычислите:

1) 5/7 х (21/20 - 7/30) + 16/21 : 8/7

2) 4/45 : (12/25 - 4/15) + 15/16 х 4/15

5/7 * (21/20 - 7/30) + 16/21 : 8/7 = 1 1/4

1) 21/20 - 7/30 = 63/60 - 14/60 = 49/60

2) 5/7 * 49/60 = (1*7) / (1*12) = 7/12

3) 16/21 : 8/7 = 16/21 * 7/8 = (2*1) / (3*1) = 2/3

4) 7/12 + 2/3 = 7/12 + 8/12 = 15/12 = 1 3/12 = 1 1/4

4/45 : (12/25 - 4/15) + 15/16 * 4/15 = 2/3

1) 12/25 - 4/15 = 36/75 - 20/75 = 16/75

2) 4/45 : 16/75 = 4/45 * 75/16 = (1*15) / (9*4) = 15/36 = 5/12

3) 15/16 * 4/15 = 4/16 = 1/4

4) 5/12 + 1/4 = 5/12 + 3/12 = 8/12 = 2/3