You need to use the same units.
Since you are told 15 min for a 45 min show, let's convert 2 hr to min.
1 hr = 60 min, so 2 hr = 120 min.
Now you can use a proportion.
15 min is to 45 min as x min is to 120 min
15/45 = x/120
45x = 15 * 120
45x = 1800
x = 40
Answer: 40 minutes
