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

Respuesta :

Answer:

$3.63

Step-by-step explanation:

A 10-minute call to France cost $3.19.

[tex](x_1,y_1)=(10,3.19)[/tex]

A 15-minute call to France costs $4.29.

[tex](x_2,y_2)=(15,4.29)[/tex]

Now we will use two point slope form

[tex]y-y_1=\frac{y_2-y_1}{x_2-x_1}(x-x_1)[/tex]

Substitute the values :

[tex]y-3.19=\frac{4.29-3.19}{15-10}(x-10)[/tex]

[tex]y-3.19=0.22(x-10)[/tex]

[tex]y-3.19=0.22x-2.2[/tex]

[tex]y=0.22x-2.2+3.19[/tex]

[tex]y=0.22x+0.99[/tex]

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

[tex]y=0.22(12)+0.99[/tex]

[tex]y=3.63[/tex]

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