Answer:
Step-by-step explanation:
let x represent the number of minutes of call.
Let y represent the remaining credit after x minutes of call.
If we plot y on the vertical axis and x on the horizontal axis, a straight line would be formed. The slope of the straight line would be
Slope, m = (12.44 - 16.78)/(54 - 23)
m = - 4.34/31 = - 0.14
The equation of the straight line can be represented in the slope-intercept form, y = mx + c
Where
c = intercept
m = slope
To determine the intercept, we would substitute x = 54, y = 12.44 and m = - 0.14 into y = mx + c. It becomes
12.44 = - 0.14 × 54 + c
12.44 = - 7.56 + c
c = 12.44 + 7.56
c = 20
The linear function becomes
y = - 0.14x + 20
