Answer:
138/18
23:3
Explanation:
There are 18 empty seats so we can already fill out the right side of our ratio (yes I said our. Oh the communism!) with 18, to make :18.
We also know that there are 156 seats, so we will subtract 18 to find the amount of the filled seats, which is 156-18 = 138
138 seats are filled.
We can put the 138 on the left side of the ratio which is now
138:18
We now divide both sides by 2 to try to get the simplified form.
138/2 = 69
18/2 = 9
69:9
Now we divide both sides by 3.
69/3 = 23
9/3 = 3
23:3
23 and 3 are both prime numbers meaning that there are no factors to divide or simplify with anymore except for the same number and 1.
The answer is 23:3