Algebra Equation - : Ask GMAT Experts
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 16 Jan 2017, 12:55

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# Algebra Equation -

Author Message
Intern
Joined: 04 Nov 2012
Posts: 3
Schools: HBS '16, Wharton '16
Followers: 0

Kudos [?]: 2 [0], given: 0

### Show Tags

18 Jun 2013, 17:32
Hi,

Question about writing equations for rate/distance problems.

If the problem states, train A starts traveling at 40 mph, and train B leaves 3 hours later at 60 mph. After how long will they catch up.

One way, correct, to write it would be : 40 (t + 3) = 60 t ---- since the distance traveled will be the same.

BUT

why can i not, and the answer is different, if i write it like this : 60 (t - 3) = 40 t ...

I am having a hard time understanding this ..... if someone could please elaborate
Veritas Prep GMAT Instructor
Joined: 16 Oct 2010
Posts: 7118
Location: Pune, India
Followers: 2128

Kudos [?]: 13625 [0], given: 222

### Show Tags

18 Jun 2013, 19:31
indiheats wrote:
Hi,

Question about writing equations for rate/distance problems.

If the problem states, train A starts traveling at 40 mph, and train B leaves 3 hours later at 60 mph. After how long will they catch up.

One way, correct, to write it would be : 40 (t + 3) = 60 t ---- since the distance traveled will be the same.

BUT

why can i not, and the answer is different, if i write it like this : 60 (t - 3) = 40 t ...

I am having a hard time understanding this ..... if someone could please elaborate

You can use either way. Note that the variable t stands for different things in the two equations.

40 (t + 3) = 60 t (t is the time for which train B travels)
t = 6 hrs
Train B travels for 6 hrs
Train A travels for 9 hrs

60 (t - 3) = 40 t (t is the time for which train A travels)
t = 9
Train A travels for 9 hrs
Train B travels for 9 - 3 = 6 hrs
_________________

Karishma
Veritas Prep | GMAT Instructor
My Blog

Get started with Veritas Prep GMAT On Demand for \$199

Veritas Prep Reviews

Re: Algebra Equation -   [#permalink] 18 Jun 2013, 19:31
Similar topics Replies Last post
Similar
Topics:
Simplify an arithmetic or algebraic representation 3 11 Jan 2016, 04:26
Equations 1 26 Nov 2015, 21:24
3 Factoring quadratic equation 3 04 Sep 2013, 09:49
Equations for 3 overlapping sets 1 21 Jun 2013, 20:28
having trouble factoring this equation 1 29 Jul 2012, 08:10
Display posts from previous: Sort by