So the equation of a line is:
y = mx + b
You are given an x and a y and a rate, which is the slope of the line (m).
The rate is given as N per unit. This means the 'unit' whatever it is referring to will be your 'x' variable.
Then solve for y-intercept (b) by subbing in your x,y values.
----> b = y - mx
Example 3:
Rate is $8 per day. Days are my x variable, Dollars are my y variable.
Given: x = 3, y = 29
b = y - mx = 29 - (8)(3) = 29 - 24 = 5
Equation of line:
y = 8x + 5
Hope this helps
