Question

Mrs. Zabel, the yearbook adviser, always likes to sell a large amount of yearbooks because after the initial set-up costs are paid, the printing is not too expensive.
If the yearbook staff sells 50 yearbooks, the cost per yearbook is $45. If they sell 125 yearbooks, the cost per yearbook is $37.50.

Assuming a linear equation fits the situation, find the price per yearbook if the staff sells 150 yearbooks.

Answer 1

(50,45)(125,37.50)
slope(m) = (37.50 - 45) / (125 - 50) = -7.5/75 = -0.1

y = mx + b
slope(m) = -0.1
(50,45)...x = 50 and y = 45
now we sub and find b, the y int
45 = -0.1(50) + b
45 = - 5 + b
45 + 5 = b
50 = b

so ur equation is : y = -0.1x + 50

so it the staff sells 150 yearbooks...
y = -0.1x + 50
y = -0.1(150) + 50
y = -15 + 50
y =  35 <== price per yearbook