pls show me how to solve this. Thank you.

QUESTION 12 10 points Save Answer 5 ranchers use a grassland to feed their cows. The ranchers must choose how many cows to raise. The benefit of raising a cow for a rancher is 100 -5 G per cow, where G is the total quantity of cows using the grassland. The marginal cost of raising a cow is 10. Hence, the net benefit of raising cows for any rancher is (100-50)g - 10g, where g is the quantity of cows raised by the rancher. What is the total number of cows using the grassland, implied by the Nash Equilibrium? O 12 O 15 O 18 O 9