Emily designed a robot that could climb down steps. she drew a graph to show the results from a test of her new robot. the graph shows the number of steps remaining over time.

what is the equation that represents emily’s situation?

a. y=−1/10x+15

b. y = 10x + 150

c. y=−10x+150

d. y=1/10x+15

The answer is A.)  

To find this answer the first thing we need to do is look at the equation of a straight line: y=mx+b

What I did first was look at b. b represents the y-intercept. By looking at the graph we can tell that the line crosses the y-axis at (0,15), so the y- intercept is 15. So our answer should at least have b=15. Using this we can go ahead and eliminate answers B & C 

Next we look at the slope (m). One way you can figure out slope is using the rise over run method. Since this line has a negative slope our rise should be a negative number. So, the only answer that should be left is A.)