jika a=-2×+3y b=-4×+5y dan c=2×-7y hitunglah nilai berikut a.a+b+c b.a-b-c c.2a-3c d.-3a-2b tolong di jawab makasih

a) a + b + c
= (-2x + 3y) + (-4x + 5y) + (2x - 7y)
= (-4x + y)

b) a - b - c
= (- 2x + 3y) - (- 4x + 5y) - (2x - 7y)
= 15y

c) 2a - 3c
= 2(-2x + 3y) - 3(2x - 7y)
= - 4x + 6y - 6x + 7y
= - 10x + 13y

d) - 3a - 2b
= - 3(-2x + 3y) - 2(- 4x + 5y)
= 6x - 9y + 8x - 10y
= 14x - 19y

maaf ya kalo tulisannya jelek