Calculating acceleration due to friction without mass?

[Amber_]

Homework Statement

Here is the problem:
You are driving at the speed of 28.4 m/s
(63.5426 mph) when suddenly the car in
front of you (previously traveling at the same
speed) brakes. Considering an average human
reaction, you press your brakes 0.505 s later.
Assume that the brakes on both cars are fully
engaged and that the coefficient of friction is
0.719 between both cars and the road.
The acceleration of gravity is 9.8 m/s 2

Calculate the acceleration of the car in front
of you when it brakes.
Answer in units of m/s 2

Note: this is the first part of a multipart question.

2. The attempt at a solution

I know exactly how I would do this problem, were the masses of the cars given. I honestly have no idea how you would get the acceleration due to friction without knowing the mass of the car. Is it possible that this is a mistake in the problem, or am I missing something?

 

[willem2]

I know exactly how I would do this problem, were the masses of the cars given.

Ok, I give you the mass. It is equal to m.

 

[Amber_]

I thought of that, but . . . oh. Oops.

Clearly I didn't think hard enough before because I didn't realize the m's should cancel out. Okay I get it now! Thanks for that.