\(-3(-2x-7y)=6x+21y\)

\(2+(-4a-5)=2-4a-5=-4a-3\)

\(-9-(-4x-3)=-9+4x+3=4x-6\)

\(-9(-4a+3)=36a-27\)

\(-2(-6p+5)+3(8p+9)=12p-10+24p+27=36p+17\)

\(-8p(-7p-3)=56p^2+24p\)

\((-5x+7)+(-9x+3)=-5x+7-9x+3=-14x+10\)

\((-7x+5)-(-6x-9)=-7x+5+6x+9=-x+14\)

\(8(3x-5y+9)=24x-40y+72\)

\((-8x+2)(4y+6)=-32xy-48x+8y+12\)

\((-4p-7)(-9p-2)=36p^2+8p+63p+14=36p^2+71p+14\)

\((a-4)(a+9)=a^2+9a-4a-36=a^2+5a-36\)

\((a-7)^2=a^2-14a+49\)

\((6x+5)^2=36x^2+60x+25\)

\((6a-7b)^2=36a^2-84ab+49b^2\)

\((a+8)(a+2)(a+5)=(a+8)(a^2+7a+10)=a^3+7a^2+10a+8a^2+56a+80=a^3+15a^2+66a+80\)

\(p(p-6)(p-7)=p(p^2-13p+42)=p^3-13p^2+42p\)

\((7x-5y)(7x+5y)=49x^2-25y^2\)

\((-2x-8)(-2x+8)=4x^2-64\)

\((a+7)(a-7)=a^2-49\)