Пошаговое объяснение:
1) 7 4/21 + 2 1/6= 151/21 + 13/6= 302/42+91/42= 393/42= 131/14= 9 5/14
2) 3 5/36 - 1 19/45= 113/36 - 64/45 = 565/180 - 256/180= 309/180=103/60 = 1 43/60
3) 3 7/30 - (4 1/6 - 1 2/15) + (4 5/9 - 4 5/9)= 1/5
1) 4 1/6 - 1 2/15 = 4 5/30 - 1 4/30 = 3 1/30
2) 4 5/9 - 4 5/9 = 0
3) 3 7/30 - 3 1/30 = 6/30 = 1/5
4) 1/5 + 0 = 1/5
4) (2 7/12 + 6 8/9) - (5 - 1 7/36 - 3 1/3)=
1) 2 7/12 + 6 8/9=2 21/36 + 6 32/36=8 53/36=9 17/36
2)5 - 1 7/36= 4 36/36 - 1 7/36=3 29/36
3) 3 29/36 - 3 1/3= 3 29/3 - 3 12/36= 17/36
4) 9 17/36 - 17/36 = 9
0,2*х =313 х = 1565