What is the best estimate for the number of people in line at 7.A.M

We have been given the equation
[tex]y=-5.131x^2+31.821x-3.333[/tex]
It represents the number of people standing to catch a commuter train x hours after 5 A.M.
Now, in order to find the number of people in line at 7 a.m. , we need to substitute x= 2 in the above equation.
[tex]y(2)=-5.131(2)^2+31.821(2x)-3.333\\y(2)= 39.785 \approx 40[/tex]
Therefore, the number of people in the line at 7 a.m. is 40
D id the correct option.