math
posted by daisy on .
The relationship described below can be modeled using an equation. Identify the variables and write an equation to solve the questions below.
Number of Credits Fees
3 2000
6 2600
9 3200
12 3800
15 4400
a) Write an equation to calculate the fees F when the number of credits n is given.
b) Use the equation from part (a) to calculate the fee for 17 credits

Graph it if you don't understand my solution:
Linear equations follow the format y=mx+b
where m is the slope and b is the yintercept.
let y= fees and x=number of credits
now calculate slope (change in y/change in x)
m=(26002000)/(63)= 200
y=200x+b
Plug in any point to find b
2000=200(3)+b
b=1400
so your equation is y=200x+1400
:P 
Looks like a straight line of slope (600/3) to me since fees increase 600 for every three credits.
F = 200 C + b solve for b
2000 = 200 (3) + b
2000 = 600 + b
b = 1400
so
Fee = 200 (Credits) + 1400
check with (15 , 4400)
4400 = (200)(15) + 1400 ?????
4400 = 3000 + 1400 ???? YES, check
Now do
Fee = 200 (17) + 1400 for part b