Question 901152
x for rectangle part length
y for rectangle part width
assume x is each diameter of the semicircles.


Part of the perimeter is from a WHOLE circle cut into two parts.
These make for {{{2*pi*(x/2)=x*pi}}}.  Reminder, x is a diameter length.


The other parts of the perimeter are 2y.


Expression for perimeter, {{{pi*x+2y}}}.
All you finally have is {{{highlight(pi*x+2y=300)}}}.
You can find the x and y intercepts so you know the restrictions but you still have two variables and just one equation.