X = -20p + 500
20p = 500 - x
p = (500 - x)/20
R = xp = x(500 - x)/20 = (500x - x^2)/20
One and 3/20 can't be simplified
X+5/5=X+9/7
-X. -X
5/5=9/7
there is no solution
we have to find equation similar to

Firstly , we can divide both sides by 2


now, we can multiply both sides by 3

we get
............Answer