Answer:
C = 1.5w + 5
Explanation:
Look at any 2 weights and costs.
For example, look at 4 lb for $11 and 8 lb for $17.
These two pieces of information can be used as two points on a line.
The points are: (4, 11) and (8, 17)
Now we need to find the equation of the line that passes through points (4, 11) and (8, 17).
We use the slope-intercept form of the equation of a line.
y = mx + b
We find the slope:
m = (y_2 - y_1)/(x_2 - x_1) = (17 - 11)/(8 - 4) = 1.5
y = 1.5x + b
Use one point, (4, 11) for x and y, and solve for b.
11 = 1.5 × 4 + b
b = 5
The equation is
y = 1.5x + 5
Since we are using C for cost and w for pounds, we write the expression as:
C = 1.5w + 5