At 5 seconds, an object's velocity is 25 meters per second. At 8 seconds, the object's velocity is 40 meters per second. Assuming a constant acceleration, what is the acceleration in meters per second per second of the object? (If necessary, round to the nearest hundredth.)

v = at + c

when t = 5, v = 25
25 = 5a + c **
when t = 8, v = 40
40 = 8a + c ***

subtract ** from ***
15 = 3a
a = 5

accelertion is 5 m/s^2