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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

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5 votes

Answer:

$3.63

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=(y_2-y_1)/(x_2-x_1)(x-x_1)

Substitute the values :


y-3.19=(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

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