Speedy printers
C = 29n
If you replace n with 2n, the cost also double. Multiplying each side by 2,
2C = 2(29n)
2C = 29(2n)
On-time printers
C = 100 + 25n
Multiplying each side by 2,
2C = 2(100 + 25n)
2C = 2(100) + 2(25n)
2C = 200 + 25(2n)
which is not the same as replacing n with 2n,
C' = 100 + 25(2n)
Then, if the number of yearbooks ordered is doubled, the cost won't double
