Answer:
52
Step-by-step explanation:
In this situation, the independent variable (x) is the amount of time in minutes. The dependent variable (y) is the number of bags remaining.
Since he is working at a constant rate, this makes it a linear function. In a linear function, the amount he had to fill to begin with is the y-intercept. Slope-intercept form is y=mx+b, where m is the slope (rate of change) and b is the y-intercept.
However, since we do not have the y-intercept, we will begin instead with point-slope form, y-y₁=m(x-x₁).
Firs twe find the slope using the formula
m = (y₂-y₁)/(x₂-x₁)
m = (32-36)/(5-4) = -4/1 = -4
Using this and the first point, we have
y-36=-4(x-4)
Using the distributive property, we have
y-36 = -4(x)-4(-4)
y-36 = -4x--16
y-36 = -4x+16
Add 36 to each side:
y-36+36 = -4x+16+36
y=-4x+52
This makes the slope -4 and the y-intercept 52; this means he originally had 52 bags to fill.