Which number produces an irrational number when multiplied by 0.4?

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.

How do i simply this expression (quadratic formula basis) on a ti-84 or normal calculator?

Ron has 8 caps and 4 of his caps are blue. thes rest of his cap are red. how many of ron's caps are red