Dilbert recently hired a mechanic to do some necessary work. On the final bill, Dilbert was charged a total of $712. $430 was listed for parts and the rest for labor. If the hourly rate for labor was $47, how many hours of labor was
needed to complete the job?

Step-by-step explanation:

Dont understand, sorry!!

i dont know it

step-by-step explanation:

answer: 204

step-by-step explanation:

we are told that the revenue is

x⋅(4080−10x)=−10x^2+4080x

this is a quadratic function, so to maximize it we should find the x-value of its vertex. recall that the x-value of the vertex of the parabola ax^2+bx+c is given by the formula −b/2a.

so in this case, we have a=−10 and b=4080, so the x-value of the vertex is

−b/2a= −(4080)/2(−10)=204