Detectives, wait until you hear about the case I stumbled upon this afternoon! I stopped in the local sweet shop for some ice cream and overheard a little boy bragging to his friends. I knew right away it was Daryl the Dirty Dealer, who makes unfair deals with innocent people. He would trade a crummy pair of old sneakers for a brand-new pair of cowboy boots. He would trade a calculator for a laptop computer!

I was outraged at what Daryl was saying to his friends.

"Friends, step right up! Order the biggest triple superscoop sundaes on the menu. The ice cream's on me today."

"Hey, Daryl," asked one of his friends. "Where did you get all the cash?"

"From Ginger, my silly little sister," Daryl bragged. "She doesn't know much about money, so I've been making deals with her every week for a month."

I couldn't believe what I was hearing!

"The first week, I traded 5 pennies for 1 quarter. I told her that it was a good deal because 5 is more than 1!"

"The second week, I told Ginger that bigger coins were worth more than smaller ones." Daryl proudly crossed his arms in front him. "So I traded 3 nickels for 3 dimes."

"On the third week, I tried something different," Daryl bragged. "I told Ginger that shiny coins were better than dirty paper money. So she gave me 1 dollar bill for 1 quarter!"

"But this week I made the dirtiest deal ever," Daryl winked. "I told Ginger that crisp new money was worth more than crumpled old money. I traded 2 new dollar bills for an old 5-dollar bill."

Super Sleuths, I was so angry I couldn't listen to another word. "Young man, you ought to be ashamed of yourself - stealing from your little sister!" I yelled. "You are the worst kind of thief!"

"Oh no, it's the Math Maven!" exclaimed Daryl. "My dirty dealings have been discovered!"

Daryl made for the door, but I swiftly grabbed him by the ear. "Come back here. You pay Ginger back at once or I'll tell your parents about your dirty little deals!"

I need your help, Super Sleuths. How much money should Daryl the Dirty Dealer return to his little sister Ginger? Hurry detectives, I don't want to have to deal with Daryl any longer than I have to!