Please help me find the mass of this object in this inelastic collision

Question

Here is the information that I have. Vinny is wearing a suit made of Velcro (the soft fuzzy side). Starting from rest, "velcro vinny" runs along level ground accelerating at 7.6m/s2 for 3 seconds. At exactly 3 seconds, he collides with a stationary crate full of ninjas (m= 209.10 kg). This crate is conveniently covered in the hard prickly side on Vinny's suit. Vinny and the CFON stick together and slide along the same level ground (mk=0.5) coming to rest 35 meters from Vinny's original starting point. What is Velcro Vinny's mass? PLEASE HELP! I AM TERRIBLE AT PHYSICS. email: [e-mail]

Answer 1

1)  V1 = a*t = 7.6*3 = 22.8 m/s

2)  P1 = P2

Mv∙v * V1 = (Mv∙v + 209.1)*V2 where V2 is the initial velocity of the 2 masses locked together.

To find V2, note that a2 = µ*g = 4.9 m/s², so from V2 = √(2a2*x) we get

V2 = √(2*4.9*35) = 18.52 m/s

Putting this value into eq 2) leads to

Mv∙v = 904.86 kg