Tomas correctly spelled 18 out of
20 words on his last spelling quiz. What
decimal represents the portion of the
words that Tomas spelled correctly?
A. 0.18
B. 0.36
C. 0.8
D. 0.9

-6 is the correct option from the above given options

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