The cost for 7 dance lessons is $82, the cost for 11 lessons is $122. write a linear equation to find the total cost (c) for (l) lessons. then use the equation to find the cost of 4 lessons.

(7,82) (11,122)

slope = (122-82) / (11-7) = 40/4 = 10

y = mx + b

slope (m) = 10

(7,82) ... x = 7 and y = 82

now we sub and solve for b, the y int

82 = 10 (7) + b

82 = 70 + b

82 - 70 = b

12 = b

so ur equation is : y = 10x + 12

when x = 4

y = 10 (4) + 12

y = 40 + 12

y = 52 < = = total cost is 52 for 4 lessons