Question

Margaret drove to a business appointment at 80 mph. Her average speed on the return trip was 70 mph. The return trip took her 1/7 hr longer because of heavy traffic. How far did she travel to the appointment?

Answer 1

Margaret traveled 80 miles to the appointment.

Step-by-step explanation:

Given,

Speed while driving for appointment = 80 mph

Speed while coming back = 70 mph

Let,

x be the time taken for the trip

y be the distance covered

Distance = Speed*Time

y = 80x     Eqn 1

Time taken in return trip = x+1/7

y = 70(x+1/7)

$y=70x+10$   Eqn 2

Putting value of y from Eqn 1 in Eqn 2

$80x=70x+10\\80x-70x=10\\10x=10$

Dividing both sides by 10

$\frac{10x}{10}=\frac{10}{10}$

x = 1 hour

Putting x = 1 in Eqn 1

$y=80(1) \\y=80$

Margaret traveled 80 miles to the appointment.

Keywords: linear equation, substitution method

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