Mary opened a savings account with a deposit of $18,000. The account earned simple interest. He did not make any additional deposits or withdrawals. At the end of 6 years, the account balance was $18,756. What is the annual interest rate on this account?

i think it is 18

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