Нанести на контурную карту крупные реки нашей страны.

1. 7 1/2 - (9 3/50 - 5 7/25) = 3 18/25
1) 9 3/50 - 5 7/25 = 9 3/50 - 5 14/50 = 8 53/50 - 5 14/50 = 3 39/50
2) 7 1/2 - 3 39/50 = 7 25/50 - 3 39/50 = 6 75/50 - 3 39/50 = 3 36/50 = 3 18/25

2. (20 1/5 - 11 2/15) - 6 1/3 = 2 11/15
1) 20 1/5 - 11 2/15 = 20 3/15 - 11 2/15 = 9 1/15
2) 9 1/15 - 6 1/3 = 9 1/15 - 6 5/15 = 8 16/15 - 6 5/15 = 2 11/15