Question 949374
x, the length of the fence.


Think step-wise through the process.


{{{3/5}}} of the fence remained when Arthur was don.
{{{3x/5}}} of the fence needs painting.


Boris did his work and this left {{{(3/4)(3/5)x}}} feet of fence still needing paint.


Chester painted the last 18 feet, that last part of remaining fence after Boris did his work.
{{{highlight_green((3/4)(3/5)x=18)}}}


{{{x=(20/9)*18}}}
{{{highlight(x=40)}}}