15. The sum of two numbers is 31/35, and their difference is 11/35. What are the numbers?

I'm at a bookstore with $\$35$ in my pocket and a $20\%$-off coupon. what is the cost of the most expensive book i can buy with my money and the coupon? (assume that there are books of every possible price in the bookstore. it's a large bookstore! )

Explain how you can show five less than a number using algebraic expression

Drawing it out would be best can you me