2y+z-z+2y=4y
x+3-5x+7=10-4x
2a+1+3-4a=4-2a
a+b-a+b-b+a=a+b
3m-2m+3+2-m=5
3y-1-2y+2+y-3=2y-2
............................................................................
1) 64m^3 -1 = (4m)^3 - 1^3 = (4m - 1)*(16m^2 + 4m + 1)
6,22+8,62+4,12=18,96
наверное так