46 burgers is the minimum amount, because there are 23 people who will each eat two burgers.
Concave up is U-shaped.
There will be a inflection/critical point f'(x) =0 then a negative slope f'(x) = neg then another inflection/critical point f'(x) =0 at the bottom of the U-shape then a positive slope to last inflection/critical point. The interval for the Concave Up shape is the first and last inflection points.
Answer: C)$117.18
$108.50 X 1.08 = $108.50

if you get a positive value, that means 2 real solutions
if you get 0, means 1 real solution only
if you get a negative value, is an imaginary root solution, same as saying no solution.
Answer:
The other angle would also measure 89°.