Due to a newly landed consulting job, Shiloh needs to make four round trip flights between Pittsburgh and Chicago. The dates of the trips are shown in the attached Excel file below. Shiloh has asked her assistant Dinesh to purchase these four round trip tickets for her.

Without a discount fare, round trip tickets between Pittsburgh and Chicago costs $500. Dinesh has found that if Shilohs stay in a city includes a weekend, he will get a 20% discount on the round-trip fare. And if Shilohs stay is more than 10 days, he will get 30% discount, and if the stay in the city is at least 21 days, there is a 35% discount.

Alas, only one discount can be applied to the purchase of any ticket. Determine how Dinesh should minimize the total cost of purchasing the four tickets.

Flight data