Atortoise is walking in the desert. it walks for 4.8 meters at a speed of 3 meters per minute. for how many minutes does it walk?

It is normally smart to write out a diagram of some sort to help you visualize the situation. I made one for this situation, although it might now suit you as well as it would me. 

The idea behind this problem is to make you understand rates. Rates being the same thing as a slope. If you have learned about that already then that will help a lot, but if you haven't then that's fine. 

So we have 4.8m and we traveled at a speed of 3 meters per 1 minute. A rate you are probably pretty familiar with is mph. Which is Miles per Hour. Or if you don't live in the U.S. Kmph. Which is Kilometers per Hour. 

What you do to solve these type of problems is you take the given value and you use the rate to get the value you want.

The easiest way to do this is to make sure the signs (Meters) "cancel" out.  

4.8m * (1min / 3m) 

To cancel something out you need to have it over itself. Here are a few examples: 

3/3 = 1
4/4 = 1 
100,000/100,000 = 1
598/598 = 1

In the case of units, such as meters. They go *poof* from the problem. 
So we have this problem: 
(4.8m*1 minute) / 3m = ? minutes

4.8/3 = 1.6

If you want the answer in fractional form... here is how you do it: (I won't explain it because you most likely won't need to do this, but if you want to know how to do it then just ask)

4(8/10) 
4(4/5)
(24/5)/3 
(24/5) * (1/3) 

24/15
8/5 is our final fractional answer!

D) the x-intercept represents adam's commission pay when he had zero total sales