An assembly line in a factory makes roofing nails. After 8 days, the total number of nails produced is 100,000. After another 4 days (on day 12), a total of 148,000 nails is produced.

Question

Which equation models the total number of nails produced?

y=8x+148,000
y=−8x+100,000
y=−12,000x+4000
y=12,000x+4000

Answer 1

they made 48000 nails in 4 days, or 12000 per day
(D) is the only equation with slope = 12000

or, doing the point-slope form
y-100,000 = 12000(x-8)
which is indeed (D)

Answer 2

Thanks oobleck.