If a large factory sells its new gadgets for $5 each, it can sell 1050 per month, and if it sells the same gadgets for $9, it will sell 900 per month. Assuming the relationship between price and sales is linear, predict the monthly sales of gadgets to the nearest whole number if the price is $12.
2
(gadgets, cost) = A(1050,5)
for B(900,9)
slope = (9-5)/(900-1050) = 4/-150 = -2/75
c = -2/75 g + b
for (900,9)
9 = -2/75(900) + b
b = 33
cost = (-2/75)g + 33
12 = -2/75 g + 33
-2/75 g = -21
g = 787.5 or 788 rounded to the next whole number