If 3 is underline in 315, what is the value of the underlined digit

Which simplifys to a+ b? a-(1-b)+1 -(1-a)-b+1 (a--1) -1)+1

Find and simplify an expression for the area of five rows of x squares with side lengths of x centimeters.

Clara schumann is buying bagels for her coworkers, she buys a dozen bagels priced at $5.49 a dozen. the bakery's cost for making the bagels is $2.25 per dozen. what is the markup rate based on selling price on a dozen bagels?