1)7y-(-1,8y)+2y=7y+1,8y+2y= 10,8y
2)-4.2y+9y-3.4y= 1,4y
3)7/20x-4/5x+0.3x= -0,15
4) 4целых5/7x+5/21x-2/3x= 3 целых 20/21
1)7y-(-1,8y)+2y=7y+1,8y+2y= 10,8y
2)-4.2y+9y-3.4y= 1,4y
3)7/20x-4/5x+0.3x= -0,15
4) 4целых5/7x+5/21x-2/3x= 3 целых 20/21