Answer:
y = 12x + 8
Explanation:
This is a straight line equation of the form
y = mx + b
where
m = slope
b = y-intercept
Here
y is the account balance in $
x = number of shoes repaired
To find slope, take points (x1, y1) and (x2, y2) on the line
slope = (y2 - y1)/(x2-x1)
Two distinct points we can see are (1, 20) and (6, 80)
slope = (80 - 20)/(6-1) = 60/5 = 12
So Alex makes $12 for every shoe repaired
The equation becomes
y = 12x + b
To find b, take point (1, 20), plug in values for x and y and solve for b
20 = 12(1) + b
b = 20 - 12 = 8
Therefore the equation of the line is
y = 12x + 8