How many quarts of a 50% solution of acid must be added to 20 quarts of a 20% solution of acid to obtain a mixture containing a 40% solution of acid?

Which equation results from adding the equations in this system? x+6y=9 and -x+2y=-15

The functions below show the amount of money bella and sweet t had saved after earning money for doing chores. which description best compares the two functions?

How many square centimeters of wrapping paper will be used to wrap the shoe box?