Tommy likes to run up and down and "up" escalator. Going up, he can cover 30 steps in 6 seconds. Going down, it takes him 15 seconds to cover 30 steps. Find Tommy's rate (in steps per second) if the escalator stopped moving.

3 steps per second.

Step-by-step explanation:

Find the Unit Rates of each going up and down:

--> 30/6 unit rate is 5 steps per second.

--> 30/15 unit rate is 2 steps per second.

Now subtract them to get the amount if the elevator wasn't moving:

--> 5-2= 3.

12.4%

Step-by-step explanation:

The results from the random sample counts 124 from a total of 1000 people that wear contact lenses. This means is the percentageof the people in the sample that wear contact lenses.Because it is a random sample, it is suppose to reflect the behavior of the total population. Then we can expect or predict  similar percentage of Americans wearing contact lenses (12.4%).