Question 319342
{{{AreaOfRectangle = Length * Width}}}
Let W be the Width. You are told {{{Length = 3W -5}}}
And also told the area is 250. So
{{{250 = (3W-5) * W}}}
{{{250 = 3w^2 - 5W}}}
{{{0 = 3W^2 - 5W - 250}}}
{{{0 = (3W + 25)(W - 10)}}}
For a product to be 0, either (3W+25) = 0  or (W-10)=0
So
{{{3W+25=0}}} 
{{{W= -25/3}}} Since the width cannot be a negative number, this is not a solution
Now check
{{{W-10 =0}}}
{{{W = 10}}}
If W = 10, then Length = 3W-5 = 30-5 = 25

The dimensions are 25x10