Zaman's father invested some money and for every Tk. 12 he invested he got a total of Tk. 15 back. If Zaman's father invested Tk. 300, how much in total did he get back?

A solid cube of side 6 is first painted pink and then cut into smaller cubes of side 2. How many of the smaller cubes have paint on exactly 2 sides?

Committee X has 4 members, committees Y has 5 members, and these committees have no members in common. If a task force is to be formed consisting of one member of X and one member of Y, how many different task forces are possible?

Susan invited 13 of her friends for her birthday party and created return gift hampers comprising one each of $3, $4, and $5 gift certificates. One of her friends did not turn up and Susan decided to rework her gift hampers such that each of the 12 friends who turned up got $13 worth gift certificates. How many gift hampers did not contain $5 gift certificates in the new configuration?

Solve the following problems: 

Katrina has a wheat business. She purchases wheat from a local wholesaler at particular cost per pound. The price of the wheat at her stores is $3 per pound. Her faulty spring balance reads: 0.9 pounds for a pound. Also, in the festival season, she gives a 10% discount on the wheat. She found that the made neither a profit nor a loss in the festival season. At what price did Katrina purchase the wheat from the wholesaler?