QUESTION IN DESCRIPTION

Question

Lydia wants to purchase guitar lessons. She sees a sign that gives the prices for 7 guitar lessons ($82) and for 11 guitar lessons ($122). How much will it cost if Lydia signs up for 13 guitar lessons?

Answer 1

let x1=7 lessons, y1 =$82, x2 = 11 lessons, y2 = $122, and x = 13 lessons

Also let y be total dollars to learn 13 lessons.

Now using 2 point form of  line equation we get:

y- y1 = (y2-y1)/(x2-x1) * (x-x1)

y - 82 = (122-82)/(11-7) * (13-7)

y - 82 =60

y= 60+82

y =  142 dollars

So Lydia will have to pay $142 for 13 lessons.