Can you guy's me out i was absent and now i don't have a clue!

For these problems you have to use PEMDAS so for problem 15 you would do the parentheses first, (21-3) you get 18 and then exponents, 3^2, you get 9, no multiplication but there is division so take your answers, 18 and 9 and divide them, you get 2, so the answer to 15 is 2.

1, 3, 5 and 6 are functions

2 and 4 are not functions

Step-by-step explanation:

because functions only have one y but can have many for x