What is the equation when Emily has 300 books if frank were to double the amount of books he has he would still have fewer books than Emily?

Let x be the number of books Frank has. The condition states that if Frank were to double his books (2x) he would still have fewer than Emily (300). So 2x < 300. This can be simplified to x < 150. Therefore, the equation is x < 150, where x represents the number of books Frank has.