Suppose gil can write a poem in 1 hour, holly can write a poem in 2 hours, and ivan can write a poem in 3 hours. Each person spends 12 hours per day writing poems and requires a wage of $10 per hour to do so. How much more would it cost a literary magazine to commission 19 poems per day than 18 poems per day?

A poem wage for Gil = number of hours * wage per hour

= 1*10 = 10$

A poem wage for Holly = number of hours*wage per hour

= 2*10 = 20$

A poem wage for Ivan = number of hours * wage per hour

= 3*10 = 30$

And all 3 of them works for 12 hours per day.

Since Gil charges least for a poem, it is always betterr to take Gil for first 12 poems.

Let us find wage for 18 poems = (wage for 12 poems from Gil) + (wage for 6 poems from Holly) = 12*10 + 6*20 = 240$

Since both Gil and Holly worked for 12 hours to complete 18 poems.

Remaining 1 poem should be written by Ivan.

And that will cost 30$.

Hence It will cost 30$ more to commission 19 poems per day than 18 poems per day.