two horses are pulling a 325 kg wagon, initially at rest. The horses exert 250 N and 178 N forward forces, respectively. Ignoring friction, how fast is the wagon moving 3.50 s later?

AFter 3.5 s, the wagon is moving at:  

Explanation:

Let's start by finding first the net force on the wagon, and from there the wagon's acceleration (using Newton's 2nd Law):

Net force = 250 N + 178 N = 428 N

Therefore, the acceleration from Newton's 2nd Law is:

So now we apply this acceleration to the kinematic expression for velocity in an object moving under constant acceleration:

a and b sometimes have a positive value

i think the answer would be reserve.