If it is the midpoint, then FG= FM+MG
Also, this means that they are of equal lenght, so
FM=MG
5y + 13= 5-3y
5y+3y=5+13
8y=18
y=[tex] \frac{18}{8} [/tex]=2.25
which means that the two halves are equal to 5y+13=5*2.25+13=24.25
and FG is double the lenght:
24.25*2=49