Hello, i'm not sure how to solve for a using the kinematic equation "don't need vf". can anybody ? heres the problem: "in an intense game of tug of war, you are pulled from your initial velocity of 2.2 meters per second, travelling 17.5 meters in 5.5 seconds. what is your acceleration as you're being pulled? "

There are varieties of kinematic equations that so long as you have 3 known variables, you can find a 4th unknown.

vi = 2.2m/s

d = 17.5m

t = 5.5s

a = ?

As can be seen here, you have 3 out of the 4 variables.  So the kinematic equation which relates these variables is:

x = vi*t + (1/2)at^2

(17.5) = (2.2)(5.5) + (1/2)a(5.5)^2  Plug in your knowns

17.5 = 12.1 + 15.1a  Combine values

5.4 = 15.1a  Isolate a

0.36 m/s^2 = a