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April 17, 2014

April 17, 2014

Posted by **dawn** on Monday, March 21, 2011 at 10:12pm.

pleassee help! thanks :)

- math - incomplete -
**Ms. Sue**, Monday, March 21, 2011 at 10:18pmHow long does it usually take them to make this trip?

- math -
**dawn**, Monday, March 21, 2011 at 10:53pmoh my gosh! so my teacher handed us two versions of this question...i didn't have that answer! sorry. the proper question i will repost.

- math -
**dawn**, Monday, March 21, 2011 at 10:58pmnever mind it does not say. does this mean the question is complete and unable to answer? its a question on an assignment and i do not know how to answer it. should ijust say uncomplete?

- math -
**drwls**, Tuesday, March 22, 2011 at 5:55amLet V1 = the original average speed and V2 = the slower average speed. You have these two equations in two unknowns:

V1 - V2 = 20 (km/h)

240/V2 - 240/V1 = 1 (hour)

You want to solve for V2. Use substitution, V1 = V2 + 20

240/V2 -240/(V2 +20) = 1

240*[1/V2 - 1/(V2+20)] = 1

20/[V2(V2+20)] = 1/240

V2*(V2+20) = 4800

You can solve this as a quadratic equation and take the positive root. You should get

V2 = 60 km/h

- math (not incomplete) -
**drwls**, Tuesday, March 22, 2011 at 10:32amNote that there was enough information provided to solve for both velocities, using simultaneous equations.

- math -
**Anonymous**, Thursday, April 14, 2011 at 9:06pmthh

- math -
**Anonymous**, Thursday, April 14, 2011 at 9:06pmI LOVE MATH

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