Вычислите:

1) х-2/3=1/18

2) 1/12+х=3/4 + 1/6

3) 19/20-х=1/4

4) х+3/20=7/10+1/4

Х-2/3=1/18

х=1/18+2/3 1/18+2/3 = (1+12) / 18=13/18

х=13/18

1/12+х=3/4+1/6

х=3/4+1/6-1/12 3/4+1/6-1/12 = (9+2-1) / 12=10/12=5/6

х=5/6

19/20-х=1/4

х=19/20-1/4 19/20-1/4 = (19-5) / 20=14/20=7/10

х=7/10

х+3/20=7/10+1/4

х=7/10+1/4-3/20 7/10+1/4-3/20 = (14+5-3) / 20=16/20=4/5

х=4/5

1) x = 2/3 + 1/18

x = 13/18

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

x = 3/4 + 1/6 - 1/12

x = 10/12 = 5/6

3) 19/20 - x = 1/4

-x = 1/4 - 19/20

- x = - 14/20

x = 14/20 = 7/10

4) x + 3/20 = 7/10+1/4

x = 7/10 + 1/4 - 3/20

x = 16/20 = 4/5