January 2008 SAT Hard Math Question HELP #18

JohnTee
Sat, 27 Jul 2013 05:20:59 +0000

Easier way…

20 mph = 10 miles = 30 minutes of travel
40 mph = 10 miles = 15 minutes of travel

45 minutes of travel (TOTAL TIME FOR THE 20 MILES)

Now, you know that it takes you 45 minutes to travel 20 miles. You have to find out how long you can travel in 1 hour, or 60 minutes. So, CROSS MULTIPLY.

45 / 60 = 20 / x

(make them vertical, they’re fractions, hard to do on forums tho.)

You will get this.
45x = 1200

Then just divide
x = 26 2/3 miles OR 80/3 miles