Help to solve this math problem! Thanks for your help!?

Let c = cash flow per share in $
and t = 9 represent 1999

The linear equation should be : c = at + b
where a, b are real number.

When t = 9, c = 1.28 :
1.28 = 9a + b ...... [1]

When t = 17, c = 1.61 :
1.61 = 17a + b ...... [2]

[2] - [1] :
0.33 = 8a
a = 0.04125

Substitute a = 0.04125 into [1] :
1.28 = 9 × 0.04125 + b
b = 0.90875

The linear equation is : c = 0.04125t + 0.90875

If t is the number of years after 1990, then you have two points of data:

(9, 1.28) and (17, 1.61)

You are told it's linear, so you can use these two points to find the equation:

y = mx + b

Slope is change in y over change in x:

(1.28 - 1.61) / (9 - 17)
-0.33 / -8
0.04125

Now that we have the slope, use one of the points to find the intercept:

y = mx + b
1.28 = 0.04125 * 9 + b
1.28 = 0.37125 + b
b = 0.90875

So your equation is:

y = 0.04125x + 0.90875