revenue of r as a function

Question

find a model that expresses the revenue r as a function of x (remember R=xp) p=-1/7x +200

Answer 1

r=xp=x(1/7x+200)=1/7+200x

so r(x)=1/7 + 200x. But that means when x=0 there's still positive revenue which doesn't make sense.

Maybe p=(1/7)x+200?

then r=xp=x(x/7+200)=x²/7 + 200x

r = (1/7)x² + 200x Then when x=0 r also = 0.