Respuesta :
Answer: the remaining credit after 94 minutes of calls is $6.84
Step-by-step explanation:
let x represent the total calling time made with the card.
Let y represent the remaining amount of credit on the card
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 = (9.78 - 15.1)/(73 - 35)
m = - 5.32/38 = - 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 = 35, y = 15.1 and m = - 0.14 into y = mx + c. It becomes
15.1 = - 0.14 × 35 + c
15.1 = - 4.9 + c
c = 15.1 + 4.9
c = 20
The linear function becomes
y = - 0.14x + 20
The remaining credit after 94 minutes of calls would be
y = - 0.14 × 94 + 20
y = - 13.16 + 20
y = $6.84
