Find the probability of selecting the same card from a deck of playing cards twice with replacement

Abox contains 1 plain pencil and 4 pens. a second box contains 5 color pencils and 5 crayons. one item from each box is chosen at random. what is the probability that a plain pencil from the first box and a color pencil from the second box are selected? write your answer as a fraction in simplest form.

If f(x) = x+8 and g(x) = 4x- 3, find (f+g)(x)

Which equation can be used to measure the density of water in a spherical water tank? let w represent the number of water particles within the region.