Question $11(6$ points$)$ Tariffs are going up this year. Let $P(x)$ be the average price of a car where $x$ represents the amount of tariff being imposed on steel. For instance, we will tuse $x=35$ to represent a $35$ percent tariff.

a$)(9$ points$)$ Suppose we know that when the steel tariff is $10$ percent then the average price of a car is increasing at a rate of $$150$ for every unit increase in the tariff. Write down an equation that corresponds to this statement.