What is the greatest integer value of y for which 5y - 20 < 0?

5y - 20 < 0 ... add 20 to both sides

5y < 20 ... divide both sides by 5

y < 20/5

y < 4 (this states that y is less then 4)

Therefore, the greatest integer that y could be is 3 (because integers cannot be fractions, they have to be whole numbers)