Question 1056647

Did I start out this problem correctly?

Find the numerator:(-3x)/(5x-20)=(?)/(40-10x)

I factored what I could and got this:(-3x)/[5(x-4)]=(?)/[-10(x-4)]

I am not sure what to do beyond this point.
<pre>Where to go next!
Multiply the fraction: {{{(- 3x)/5(x - 4)}}}, by {{{(- 2)/(- 2)}}}, to get: {{{(- 2)(- 3x)/(- 2)(5)(x - 4)}}}, and subsequently: {{{highlight_green(matrix(1,7, 6x/(- 10(x - 4)), "=", 6x/(- 10(x - 4)), so, "?", "=", 6x)))}}}