Help with QR question

[Toothy2012]

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How long would it take for bullet A traveling at a constant speed of 10 m/s to begin surpassing bullet B traveling constantly at 8 m/s from the time when bullet A was spotted to be 12 m behind bullet B?

A.2 secondsB.4 secondsC.6 secondsD.8 secondsE.10 seconds

The answer is C, and the explanation is a little confusing. I was wondering if anyone knows of an easy way to approach this problem.
Thanks!

 

[fireblast713]

Bullet Train A is traveling 2m/s faster then Bullet Train B the distance separating them is 12m 12m/(2m/s) is 6s.

 

[SanOnofre2002]

Set up a rate eqn where each will become equal.
(10m/s)t = (8m/s)t + 12m Solve for t
So the distance the first one travels will equal the distance the second one travels plus its 12m head-start.

 

[Toothy2012]

Thanks a lot guys, both techniques seem much easier than the explanation.😀