Question 960758

{{{(a-b)^3=(a-b)(a^2-2ab+b^2)}}}

compare to

{{{(4x-5y)(16x^2+kxy+25y^2)}}} 

so, {{{a=4x}}}, {{{b=5y}}} and {{{kxy=2ab}}}=>

{{{kxy=2*4x*5y}}}

{{{kxy=40xy}}}

{{{k=40}}}

so, your answer is D. {{{40}}}