Tolong diisikan dengan cara yg lengkap soalnya msh bingung dengan cara yg diberi guru.

3a) (42n + 35m + 7) - (-50m - 20n + 9)
= 42n + 20n + 35m + 50m + 7 - 9
= 62n + 85m - 2

b) (5x + 3) - (x - 1)
= 5x - x + 3 + 1
= 4x + 4

c) (2y + 15z) - (4y - 8)
= 2y - 4y + 15z + 8
= - 2y + 15z + 8

4) (5z + 3) - (2z - 7)
= 5z - 2z + 3 + 7
= 3z + 10

5) (6x + 4) - (x - y)
= 6x - x + y + 4
= 5x + y + 4

6) (5x - 9) - (7x + 15y)
= 5x - 7x - 15y - 9
= - 2x - 15y - 9

b) (5y - 3x - 4) - (5x - 3y + 7)
= - 3x - 5x + 5y + 3y - 4 - 7
= - 8x + 8y - 11