15.2
1)
3ав + 9ас + 27аd = 3a * (b + 3c + 9d).
2)
4ху + 8хz - 16х = 4х * (у + 2z - 4),
3)
0,2mn - 0,8mk + 1,6m = 0,2m * (n - 4k + 8),
4)
9tk - 18tx + 27t = 9t * (k - 2x + 3),
5)
0,75аt + 3/4ах - 9/16а = 3/4аt + 3/4ах - 9/16а = 3/4а * (t + х - 3/4),
6)
-2/3dх + 4/9dу - 8/9d = -2/3d * (х - 2/3у + 4/3) = -2/3d * (х - 2/3у + 1 1/3)