Math Riddles

Question: If I am buying 9 for $1, 18 for $2, 125 for $3, and 1222 for $4, then what am I buying?

Question: There are 2 brother's, the oldest is 4 yrs old. The little brother Is 1/2 his age. When the big brother is 100 how old will the little brother be?

Question: someone came into my shop and stole 100 dollars from the register without my knowledge. the person came back 5 minutes later with the same 100 dollars and bought 70 dollars in items and i gave him back 30 dollars change. How much did i lose?

Question: sedentary stop + sudden start = ?

Question: Matt's teacher asked him, "What is 3+3?" Matt answered, "8," Matt is correct. How is this possible?