Marginal Product of Labor and optimal units of labor?

Question

The question:

Suppose a producer has a production formula of:

MPL (Marginal Product of Labor) = 80 - L

The product that is sold to the market is sold at P = 8

The labor is bought for w = 400

Both the product and labor are traded in markets that are characterized by perfection competition.

Why is the following true?: 

If the wage level rises above 640, the producer will not hire any labor at all

Under the above conditions, the producer will employ 30 units of labor

If the price of the product rises (all else being equal), the producer will want to hire more units of labor

/ David

Answer 1