\(a,A=2x^2-10x-x^2+4x-4-x^2+9\\ =-6x+5\)
\(b,B=x^2+2x+1-4x^2+4x-1+3x^2-75\\ =6x-75\\ c,C=2\left(9x^2+30x+25\right)-2\left(9x^2-1\right)\\ =18x^2+60x+50-18x^2+2\\ =60x+52\)
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