A factory owner who employs m workers find that they produce k=1.6m(1.6m+40)^3/2 units of product per day.

The total revenue R in dollars is R=489k/(310848+4k)^1/2

So when there are 20 workers, the price per unit is____ dollars

When there are 20 workers, the marginal revenue is ______ dollars/(one unit of product)

The steps that i have done so far is i took the 20 and plugged it into k=1.6(20)((1.6(20)+40))^3/2 and I got 19550.088

and the second answer i tried to solve it by placing the answer that i got from the previous questions which was 19550.088 and plugged it into R=489(19550.088)/(310848+4(19550.088)^1/2 and I got 15326.951

The answers don't seem to be correct. Could someone tell what i am doing wrong please.