Answer:
Step-by-step explanation:
let x represent the number of minutes of call made.
Let y represent the cost for 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 = (10.86 - 5.91)/(10 - 5)
m = 4.95/5 = 0.99
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 = 10, y = 10.86 and m = 0.99 into y = mx + c. It becomes
10.86 = 0.99 × 10 + c = 9.9 + c
c = 10.86 - 9.9
c = 0.96
The linear function becomes
y = 0.99x + 0.96
Therefore, for $12, the number of minutes would be
12 = 0.99x + 0.96
0.99x = 12 - 0.96
0.99x = 11.04
x = 11.04/0.99
x = 11.15 minutes
