A distance runner is running an 18-mile race. So far, she has run 43% of the race. Which would be the best way to estimate the number of miles the runner has run so far?
Find 40% of 10.
Find 40% of 20.
Find 50% of 10.
Find 50% of 20.

step-by-step explanation:

the shape,the size and the distance

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

answer: what are the following choices