Question

And international calling plan charges a rate per minute plus a flat fee. A 10 minute call to France costs $4.29. Right and solve a linear equation to find the cost of a 12 minute call to France

Answer 1

The cost of a 12 minute call to France is $ 3.63

Explanation:

given:

The cost of 15 minute call to France = $ 4.29

The cost of 10 minute call to France = $ 3.19

To Find :

The cost of a 12 minute call to France = ?

Solution:

Let the flat fee be X

and the cost per minute be Y

so the 15 minute call to France will be

X + 15(Y) = 4.29---------------------------(1)

the 10 minute call to France will be

X + 10(X) = 3.19----------------------------(2)

Subtracting (2) from (1)

X + 15(Y) = 4.29

X + 10(Y) = 3.19

- - -

---------------------------------

5Y = 1.10

--------------------------------

`Y =(1.10)/(5)`

Y = 0.22

So the cost per minute of a call = $0.22

substituting the values in (1)

X + 15(0.22) = 4.29

X + 3.3 = 4.29

X = 4.29 -3.3

X = 0.99

Now the cost of 12 minute call is

=>X + 12(Y)

=> 0.99 + 12(0.22)

=> 0.99 + 2.64

=> 3.63