To prepare for a bake-off, Rebecca used 0.83 kilogram of flour each day for 3 weeks. How many grams did Rebecca use in those 3 weeks?

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