Question

16. Scott and his wife Maria have cell phone plans in which they pay for each call minute and text message

they send Last month, Scott used 95 call minutes and sent 207 text messages for $23.55. Maria used
162 call minutes and sent 124 text messages for $17.26. Find the cost for each call minute.
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Answer 1

The cost for each call minute is $0.03 or equivalently 3 cents.

Explanation:

We let the cost for each call minute be x and the cost for each text message be y. Scott's cost function in terms of x and y is;

95x + 207y = 23.55............. (1)

On the other hand, Maria's cost function in terms of x and y is;

162x + 124y = 17.26.............. (2)

Therefore, we have two equations in x and y which can be solved simultaneously.

In order to determine the cost for each call minute, we shall simply determine the value of x.

Using elimination method, we can eliminate y and determine x;

We multiply the first equation by 124,

11780x + 25668y = 2920.20..........(3)

We then multiply the second equation by 207,

33534x + 25668y = 3572.82........(4)

Subtracting equation 3 from 4 yields;

21754x = 652.62

x = 0.03

Thus the cost for each call minute is $0.03 or equivalently 3 cents.