The price of a stock decreased $2 per day for four consecutive days. what was the total change in value of the stock over the four day period

Determine whether the set of whole numbers is closed under addition. explain why the set is or is not closed. give an example.

International calls require the use of a country code. many country codes a 3-digit numbers. country codes do not begin with a 0 or 1. there are no restrictions on the second and third digits. how many different 3-digit country codes are possible?

It is given that the quadratic equation hx²-3x+k=0, where h and k are constants, has roots [tex] \beta \: and \: 2 \beta [/tex]express h in terms of k