y = 3x + 11
Since we only have 2 data points, let's assume a linear relationship for the function. So the formula will be of the form
y = ax+b
where
a = slope of the line
b = y-intercept of the line.
Let's calculate the slope first.
The slope is the change in y divided by the change in x. So
(35-20)/(8-3)
= 15/5
= 3
Our equation now becomes
y = 3x + b
Let's calculate b. Do so by substituting the x and y values of a known point. It doesn't matter which point you use. So
20 = 3*3 + b
20 = 9 + b
11 = b
And to prove that it doesn't matter which point, let's do it again.
35 = 3*8 + b
35 = 24 + b
11 = b
So the y intercept is 11. And the equation for the line is now
y = 3x + 11
