A sales team estimates that the number of new phones they will sell is a function of the price that they set. They estimate that if they set the price at x dollars, they will sell f(x)=4080−10x phones. Therefore, the company's revenue is x⋅(4080−10x).

Find the price x which will maximize the company's revenue.

distance covered by pamela in 9 l of fuel = 99km

let us apply unitary method here.

distance covered by pamela in 1 l of fuel =99/9 =11 km

now let us find distance covered by pamela if she has 12 l of fuel.

distance covered in 12 l = distance covered in 1 l of fuel * 12

we know that distance covered by here in 1 l is 11 km.

so distance covered in 12 l of fuel = 11*12 = 132 km.