Question 841603
x for length, y for width

{{{x=y+4}}} from description.
area, {{{xy=60}}}.  Substitute to obtain {{{(y+4)*y=60}}}
{{{highlight(y^2+4y-60=0)}}}-----this is one of the equations you would use.
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{{{Discriminant= 4^2-4(-60)=16+240=256=16^2}}}
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{{{y=(-4+- 16)/2}}} and you want the POSITIVE result.
{{{highlight(y=6)}}}
Note that the quadratic expression is also factorable:
{{{(y-6)(y+10)=0}}}
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You can now find x because you have the value of y.
{{{highlight(x=10)}}}