What amount of a 60% acid solution must be mixed with a 35% solution to produce 300 mL of a 55% solution?

A 300 gallon tank initially contains 90 gallons of brine containing 400 Ibs. of salt. Brine containing 1 lb. of salt per gallon enters the tank at 4gal/s, and the well-mixed brine flows out of the tank at 1 gal/s. How much salt will the tank contain when it is full of brine?

A molding machine produces 4-centimeter cubes of plastic. The volume of molten plastic needed to produce these cubes is 11% more than the volume of plastic in the solid cubes. Find the amount of molten plastic needed to produce 100 cubes. (Note: 1 milliliter = 1 cubic centimeter.)

How many milliliters of a  3.2%  bleach solution must be mixed with a  20%  bleach solution to produce  300   mL  of a  6%  bleach solution?