the plot: x meters wide and (x+30) meters long with an area of 15000 m^2. the equation you're searching for is:
x meters * (x+30) meters = 15000 m^2 or
x^2 + 30x m^2 = 15000 m^2 and
x^2 + 30x - 15000 = 0 <== that's the equation.
ans: x^2 + 30x - 15000 = 0
