Question 953189
<i>The length of a rectangle is k cm more than m times its width. if the area of the rectangle is A sq cm, find the width</i>


L for length
w for width
{{{system(L=k+mw,wL=A)}}}


UNKNOWNS are w and L.
KNOWNS are {{{system(k=4, m=3, A=15)}}}.


Solve the first system for w.  A substitution, simplification, and general solution of a quadratic equation will bring you to the symbolic answer, and you can then substitute the known values and evaluate.  You can also choose to substitute the values into the symbolic form quadratic equation, in case it were factorable.