$30/ 3 sweatshirts = $10 /shirt
$ 10/shirt * 4 shirts = $40
It would cost $40
The function
f(x) is even
g(x) is neither even nor odd
h(x) is odd
Steps:
for an even function it holds that f(-x) = f(x):
f(-x) = (-1)^6 x^6 - (-1)^4 x^ 4 = x^6 - x^4 = f(x) => f is even
for an odd h(x) it holds that h(-x) = -h(x):

It is easy to show that g(x) does not match any of the two possibilities above.
Y=15+5g
Y is the total cost in one month. 15 is the cost of the membership and 5 is the amount you paid to see the game. G is the variable for the amount of games. You multiple the g by 5 to get the total cost of games per a month that you went and saw. Than you add the base cost of 15 or your starting point. And you get your total cost.
The answer to your question is 2 and 4.