Question 979837
Present length and width are L and w.
Present area A=240, and keeping this the same after rebuilding is wanted.


CONTINUING TO WORK IN SYMBOLS, remove h feet from length and increase width by k feet.  h=4 and k=3.



{{{system(wL=A,(w+k)(L-h)=A)}}}.


Your factor of 2  is a mistake.  You are possibly confusing the example problem with uniform-width border type rectangular area problems.