Suppose your firm faces a demand curve of (P = 90 – .30Q) and the marginal cost of production is $10/ unit. Find the profit- maximizing output and…

Suppose your firm faces a demand curve of (P = 90 – .30Q) and the marginal cost of production is $10/ unit.

1. Find the profit- maximizing output and price.
2. Is this outcome on the elastic, inelastic, or unitary elastic part of the demand curve?

Question: I need some assistance solving the following portion of the solution…

0.3Q = 90 -P

Q = 1/0.3(90-P)

ΔQ/ ΔP = – 1/3