Answer:
18 hours
Step-by-step explanation:
You know that 15cm burns in 6 hours. That means that for every 15cm that burns after that, it will be another 6 hours for each.
This gives us the means to find out how long it takes for the 45 cm candle to burn.
We want to know how many 15 cm candles fit into this 45 cm candle. To do this, we must divide: 45 ÷ 15 in order to find how how many 15 cm and 6 hour-burning candles make up the 45 cm candle
45 ÷ 15 = 3, so 3 candles, each of which take 6 hours to burn, fit into the candle
Now, all we have to do is multiply 6 by 3 in order to find out how many hours it takes for 3 candles to burn!
6 • 3 = 18, so it will take 18 hours for the candle to burn
