Вычислить: а) 29/36+5/54; б) 0,36-9/75+2/15; в) (1/2-1//4-1/5) №2 решить уравнения: а) 3/4-(х+1/20)=1/5 б) 2/3-(х-1/21)=2/7

ответы смотри на фото

1.
29/36 + 5/54 = 174/216 + 20/216 = 194/216 = 97/108
0,36 - 9/75 + 2/15 = 36/100 - 9/75 + 2/15 = 108/300 - 36/300 + 40/300 = 112/300 = 28/75
(1/2 - 1/3) - (1/4 - 1/5) = (3/6 - 2/6) - (5/20 - 4/20) = 1/6 - 1/20 = 10/60 - 3/60 = 7/60

2.
a) 3/4 - (x + 1/20)= 1/5
3/4 - x - 1/20 = 1/5
3/4 - x = 4/20 + 1/20
3/4 - x = 5/20
-x = 5/20 - 15/20 = -10/20
x = 1/2
б) 2/3 - (x - 1/21) = 2/7
2/3 - x + 1/21 = 2/7
2/3 - x = 6/21 - 1/21
2/3 - x = 5/21
-x = 5/21 - 14/21 = -9/21 = -3/7
x = 3/7