Lisa purchased a hat for $10, a purse for $20, and a book for $23.the sales-tax rate was 7.2 percent. what was the total amount she paid?

How many 3-digit numbers can you write using only digits 1 and 7? (of course, digits can repeat.) how many 3-digit numbers can you write using only digits 1 and 7? (of course, digits can repeat.)