Hi there!

Use the kinematic equation to solve for acceleration:

Where:
vf = final velocity
vi = initial velocity
t = time
Plug in the given values:

Answer:
Ms. Kang is incorrect because there is only one solution to that equation and that is b=5/3
1)( 15+cj)^3 for j = 5 and c = , ( 15+6*5)^3 = (45)^3 = 91125