A zookeeper realized that an alligator in the zoo is now four times the age that it was 15 years ago. How old is the alligator now ?

Which of these choices show a pair of equivalent expressions?

International calls require the use of a country code. many country codes a 3-digit numbers. country codes do not begin with a 0 or 1. there are no restrictions on the second and third digits. how many different 3-digit country codes are possible?

Which expression is not a polynomial?