Please please please please please please help

Kapil needed to buy a long wooden beam. he went to two sawmills that each charge an initial fee plus an additional fee for each meter of wood. the following equation gives the price (in dollars) of a wooden beam from the first sawmill as a function of its length (in meters). p = 5+20xp=5+20x

What numbers are included in the set of integers? what numbers are not included?

How do you determine if an ordered pair is a solution to a given equation?