Question

The cost for 7 dance lessons is $82. The cost for 11 lessons is $122. Write and solve an equation to find the cost of 4 lessons.

Answer 1

$52

Explanation:

Let x = number of lessons.

Let y = cost of x lessons.

Use the given information as two points on the line.

(7, 82) and (11, 122)

y = mx + b

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

y = 10x + b

82 = 10 × 7 + b

b = 12

y = 10x + 12

For 4 lessons, x = 4

y = 10x + 12

y = 10 × 4 + 12

y = 52

Answer: $52