a) -2a +3b - a -5b= -3a-2b
b) 2a-b-4a+6b+8b+a= -a+13b
c) -2x+3y+4x-7y+3x+9y=5x+5y
d) -[tex]x^{2}[/tex]+3x-1,3[tex]x^{2}[/tex]-3,4x+1,9= -2,3[tex]x^{2}[/tex]-0,4x+1,9
e) 14[tex]a^{2}[/tex]x+ ax +2,1[tex]a^{2}[/tex]x-5ax-[tex]a^{2}[/tex]x = 10,9[tex]a^{2}[/tex]x-4ax
f) 3x + 2y-(7x+y+4x+10y)= 3x + 2y-7x-y-4x-10y= -8x-9y