Alice bought wallets at $3 each and sold them at $7 each. The customers who bought two wallets from her were given one wallet free. Yesterday, all her customers either bought one or two wallets. At the end of the day, she had given away 60 wallets and earned $540. How many customers bought only one wallet?

Rick sold a total of 90 chickens and ducks. He earned a total of $4 in every duck he sold and lost $2 on every chicken he sold. On the whole, he earned a total of $222. How many ducks and chickens did he sell?

Rick sold a total of 90 chickens and ducks. He earned a total of $4 in every duck he sold and lost $2 on every chicken he sold. On the whole, he earned a total of $222. How many ducks and chickens did he sell?

65% of the members in the IT club were male. When 212 more members joined the club, the number of male members increased by 60% while the number of females= members increased by 60%. How many members were there in the end?

There were some red pens and blue pens in a box. 30% of the pens were red. When 82 pens were added, the number of red pens increased by 20% while the number of blue pens increased by 50%. How many blue pens were there in the box in the end?