Question 819510
What do you mean?  Which variable is the function name?  l or w? If these are the variables, you have already shown the equation for perimeter in standard form.  All you can do is say, {{{2*l+2*w=30}}}.


Avoid confusion in reading.  Use a different variable name for LENGTH, maybe choosing L, or x, or y.  The lower case L has the same appearance as the digit for "one".