Need help with 20-23 please. geometry

The table shows a pattern of exponents. what is the pattern as the exponents decrease?

Jenisey has $24 to spend on seven pencils. after buying them she had $10. how much did each pencil cost.?

You got a job selling magazines door-to-door. you are paid $100 per day plus $1.50 for each magazine you sell. which recursive formula models this situation?