If Jill has $8.75 and Jack has 3 times that

Jack has $26.25
He spent $5.00

He has $21.25 left
For this case we have the following equation:
f (x) = x ^ 2 + bx-49
Deriving we have:
f '(x) = 2x + b
We match zero:
0 = 2x + b
We clear x:
x = -b / 2
The axis of symmetry is at x = 8, therefore:
x = -b / 2 = 8
Clearing b:
b = -2 * (8)
b = -16
Answer:
the value of b is:
b = -16
To answer this item, we use dimensional analysis and conversion factor, 1 revolution is equal to 2π rad. Using the concept and the given,
n = (14.2 revolutions / 8 seconds)(2π rad/1 rev)
n = 11.15 rad/s
Thus, the angular velocity is equal to 11.15 rad/s.
ST=4
3x-8+x=2x
4x-8=2x
-8=-2x
4=x
Hope I’m not too late !