Question

your roommate pays the water, gas, and electric bills every month and asks you and your other roommate to each pay a third.

1. how much do you owe your roommate for the month of december?

december utilities-
water: $109.45
electric: $128.52
gas: $271.93

Explanation:

Step1: Calculate total utility bill

Add water, electric and gas bills:
$$109.45 + 128.52+271.93$$
$$=(109.45 + 128.52)+271.93$$
$$=237.97+271.93$$
$$=509.9$$

Step2: Calculate your share

Since you pay a third of the total bill:
$$\frac{509.9}{3}\approx169.97$$

Answer:

$169.97$