A company that makes hair-care products had 7,000 people try a new shampoo. Of the 7,000 people, 21 had a mild allergic reaction. What percent of the people had a mild allergic reaction? (Decimal form)

The area of a rectangle is 10 cm^2. one side of the rectangle is x cm. express the perimeter of the rectangle in terms of x and show that this rectangle cannot have a perimeter of 12 cm. the perimeter of the rectangle in terms of x is __ cm