Peter R. answered 09/12/23
Experienced Instructor in Prealgebra, Algebra I and II, SAT/ACT Math.
First find the slope (m in the linear equation y = mx + b)
(y2 - y1)/(x2 - x1) that's rise over run
(3300 - 2000)/(10 - 5) = 1300/5 = 260
y = 260x + b.
Now need to find b (y-intercept). Use either pair: Ex: 3300 = 260(10) + b
b = 3300 - 2600 = 700.
So y = 260x + 700
For 20 heaters: y = 260(20) + 700 = 5200 + 700 = $5,900.