Question 7613
({{{3z^2}}} + 7z + 9) + ({{{6z^2}}} + 3z -3) - ( {{{-5z^2}}} -8z)
={{{3z^2}}}+7z+9+{{{6z^2}}}+3z-3+{{{5z^2}}}+8z
={{{14z^2+18z+6}}}
={{{2(7z^2+9z+3)}}}