Would somebody help me with my math please

Landon wrote that 3−2.6=4. which statement about his answer is true?

Ineed someone to me answer my question i have to have this done and knocked out

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! )