The sum of two numbers is 40 one number is 4 times as large as the other what are the numbers

How to do this , and can some one explain

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

The area of the map is the product of the length and width. write and expression for the area as the product of the two binomials do not multiply