Explain how knowing 1+7 you find the sum for 7+1

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.

For what values of the variable x is the expression square root of 7x+14+ square root of 7-x a real number?

Which strategy is used by public health to reduce the incidence of food poisoning?