Решите уравнение 1 1/4 - (1/15+1/10+x) = 3/4

1 1/4 - (1/15 + 1/10 + х) = 3/4

5/4 - (2/30 + 3/30 + х) = 3/4

- (5/30 + х) = 3/4 - 5/4

- (5/30 + х) = - 2/4

5/30 + х = 2/4

1/6 + х = 1/2

х = 1/2 - 1/6

х = 3/6 - 1/6

х = 2/6

х = 1/3

проверка:

1 1/4 - (1/15 + 1/10 + 1/3) = 3/4

5/4 - (2/30 + 3/30 + 10/30) = 3/4

5/4 - 15/30 = 3/4

5/4 - 1/2 = 3/4

5/4 - 2/4 = 3/4

3/4 = 3/4