I drove to the beach at a rate of 40 miles per hour. If I had driven at a rate of 30 miles per hour instead, then I would have arrived 20 minutes later. How many miles did I drive?

aperson May 20, 2020

#5**+1 **

Guest, it's obviously not 70. Use *your *brain. And if you math teacher says 70 is the answer then he/she's obviously incompetent.

Let's say x is the time in hours.

Since it would take 20 more minutes, so we have 20/60 = 1/3.

TRIP____________speed______time___________distance

Actual___________40________x______________40x

Hypothetical_____30_______x+30/40_________30(x+1/3)

So the distances are equal so

40x = 30(x+ 1/3)

40x = 30x + 10

10x = 10

x = 1

Now let's plug x in. x * 40 = 40 so 40 miles.

Checking...

40 mph for 40 miles means 1 hour, 30 mph for 40 miles means 1 1/3 hour, and 1 hour is 60 minutes, 1 1/3 hour is 80, 80-60 = 20.

Boom.

Guest, use *your* brain.

If you don't understand anything feel free to ask.

hugomimihu May 20, 2020