since f'(5) = 2
and
f''(x) < 0 for x>=5
it means that 2 is the highest slope for x>=5
so
the highest value for f(x) can be found with the linear approximation with slope 2 through the point 5,20
y = 20 + 2*(x-5) -> y = 20 +2x -10 - > y = 2x + 10now y(7) = 24but it cant really be 24 since the slope decreasing so I would say the possible values are 20,22
