How can the closure property be applied to addition and subtraction of polynomials with integer coefficients?

Charlie is a car salesman he earns $800 plus a 9% commission on all of her sales for the week if charlie receive the payment for $1960 this week how much where is total sales

What is the equation of the graph below? y=sec(x)-4

The weight of an object in a particular scale is 175.2 lbs. the measured weight may vary from the actual weight by at most 0.1 lbs. what is the range of actual weights of the object