How much 9% saline solution should Kent mix with 80 cubic centimeters of a 19% saline solution to produce a 13% saline solution?

A33 gram sample of a substance that's used to detect explosives has a k-value of 0.1473. n = noekt no = initial mass (at time t = 0) n = mass at time t k = a positive constant that depends on the substance itself and on the units used to measure time t = time, in days