The cost for 7 dance lessons is $82. the cost for 11 is $122. write a linear equations to find the total cost c for l dance lessons. how much for 4 lessons?

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

y = mx + b
slope(m) = 10
(7,82)...x = 7 and y = 82
now we sub
82 = 10(7) + b
82 = 70 + b
82 - 70 = b
12 = b

equation is : y = 10x + 12
or, in this problem, it is : C = 10L + 12 <== ur equation

if there were 4 dance lessons.
C = 10(4) + 12
C = 40 + 12
C = 52 <== it would cost $52 for 4 dance lessons.