I'm literally stuck on this question. Find the marginal revenue equation and the marginal revenue production of the given number of bushels....

I'm literally stuck on this question. Please help!!

Find the marginal revenue equation and the marginal revenue production of the given number of bushels.

r(x)=0.0649x^2+1.3687+2.4273

what is the marginal revenue for 200,000,000? 950,000,000?