Question

An international calling plan charges a rate per minute plus a flat fee. A 10-minute call to France cost $3.19. A 15-minute call to France costs $4.29. Write and solve a linear equation to find the cost of a 12-minute call to France

Answer 1

Answer:

$3.63

Step-by-step explanation:

A 10-minute call to France cost $3.19.

$(x_1,y_1)=(10,3.19)$

A 15-minute call to France costs $4.29.

$(x_2,y_2)=(15,4.29)$

Now we will use two point slope form

$y-y_1=\frac{y_2-y_1}{x_2-x_1}(x-x_1)$

Substitute the values :

$y-3.19=\frac{4.29-3.19}{15-10}(x-10)$

$y-3.19=0.22(x-10)$

$y-3.19=0.22x-2.2$

$y=0.22x-2.2+3.19$

$y=0.22x+0.99$

y is the cost and x is the number of minutes

Now we are suppose to find cost of a 12-minute call to France

Substitute x = 12

$y=0.22(12)+0.99$

$y=3.63$

Hence the cost of a 12-minute call to France is $3.63