What's the question? there isn't enough info to help.
I'm not sure what your variables are, but I will try task 3 with you.
y=$500(in billions)
x= the number of years that have passed since 2009
percentage of decrease: 1 - % =
so your formula will look like this: y(1 - %)^x
Answer:
y = -1/3x - 5/3
Step-by-step explanation:
The slope of a line is the ratio of vertical distance to horizontal distance between the points. Since the line has to cross through the point (-5,0), count out the slope -1/3 by moving down 1 unit and to the right 3 units. This places the line between -1 and -2 on the y-axis. Looking at the options listed for b in y = mx + b. b = -5/3 is the best option and is between -1 and -2.
The answer to number 18 is - 0.25 or 1/4
If you need help with the other ones ask.
<em>Hope this will help :)</em>