1)(2a-3x)+(-13+5x) -(5,2-y)=2a-3x-13+5x=2a+2x-13
2)-(5,2-y)+(3,2x-4y)
=-5,2+y+3,2x-4y=-5,2-3y+3,2x
3)(-3x²-6x+1)-(-2x²+3x-1)=-3x²-6x+1+2x²-3x+1=-x²-9x+2
4)(-5a²-10a+12)-(3a²+10a-7)=-5a²-10a+12-3a²-10a+7=-8a²-20a+19
5)(-2a+13b)+(2a-13b)=-2a+13b+2a-13b=0