It took Matt twice the time to drive from home to work as it took him to drive back home from work by the same route. If Matt averaged 30 miles per hour (mph) on his drive to work, his average speed for the entire round trip was A) 30 mph
B) 25 mph
C) 40 mph
D) 15 mph

C: 40 mph

Step-by-step explanation:

We are told that it took Matt twice the time to drive from home to work as it took him to drive from work to home.

This means;

2(time to drive from home to work) = time to drive from work to home

2(30) = time to drive from work to home

time to drive from work to home = 60 hr

We are told it took Matt 30 miles/hr to drive from home to work.

Thus;

Time from home to work = x/30 hours

Time to drive from work to home = x/60

Total distance = x + x = 2x

Thus,average speed = 2x/(x/30 + x/60) = 2x/(3x/60) = 120x/3x = 40 mph

4 and 5)16.97 or 12√2

6)15.59 or 9√3

7)y = 15.59 or 9√3     x =27

8)17.80