Question 883602
Really wanting to know how to solve this kind of problem for the future is a good goal.  Here is a way to think of this problem.


ANYTHING of the form:
<i>The width of a certain rectangle is k meters more than m times its length. If the perimeter of the rectangle is p meters, what is the length of the rectangle?</i>


Let w = width
Let L = length  (UPPER CASE, so as not confuse with digit ONE nor lower case L)


Description relating length to width, {{{highlight_green(w=k+mL)}}};
Accounting for Perimeter, {{{highlight_green(2w+2L=p)}}}.
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Those are two simultaneous equations and the UNKNOWN variables are w and L.  Solve the system for w and L.  When you substitute the given values for k and m, you can compute the values for w and L.


The idea is to symbolically solve for w and L and have formulas for w and L; BEFORE using the given values for k and m.


I am leaving this solution post as it is so that you can do what was described for the rest of the solution process.  Note that this posting serves as a lesson in how to solve of rectangle problem of this type.