b. Kelly realizes once she gets to Round Rock that she left her Art project (a m
ID: 3135913 • Letter: B
Question
b. Kelly realizes once she gets to Round Rock that she left her Art project (a major grade) at her mother's house in Plano over Spring Break. She would not have time to have it shipped before it is due the next day and convinces her brother to meet her part of the way. If the average speed limit from Plano to their meeting point (on the North side of West, TX) is 65 miles per hour, and the average speed limit from Round Rock to their meeting point is 75 miles per hour, how many miles will Kelly's brother have to drive before he reaches Kelly if the driving distance between them is 196 miles and they drive the same amount of time?Explanation / Answer
b. The driving distance between Plano and Round Rock is 196 miles. Let Kelly’s brother drive x miles before he reaches Kelly at the meeting point which is 196-x miles from Round Rock.
At 65 m.p.h., a distance of x miles will take x/65 hours. Also, at 75 mph, a distance of 196-x miles will take (196-x)/75 hours. Since Kelly and her brother drive for the same amount of time, we have x/65 = (196-x)/75 or, 75x = 65(196-x) or, 75x +65x = 65*196 or, 140x = 12740 so that x = 12740/140 = 91.
Thus, Kelly’s brother will have to drive 91 miles before he reaches Kelly.
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