Identify each following representation as a function or nonfunction and explain your reasoning.

a) and c) - function, b) and d) - nonfunction

Step-by-step explanation:

As per definition, a function is such a relationship that each input has exactly one output

Considering this we observe that:

a) functionb) not a function as input of -1 has two different outputs o and 1c) functiond) not a function as input of 0 has two different outputs 0 and 0.5

Hello there! 
You can use the equation:
504 ÷ 6
84
The hotel can buy 84 pillows.
Hope this helped! :D