Answer: 9 hrs for 45cm of snow to fall
Step-by-step
If 30cm = 6 hrs
Then divide 30/6 to get the unit rate of the amount of snow per hr
Which is 5/1
So 5cm per hr
Then add 30+5+5+5 to get 45
And since we know 5cm equal 1 hr
Add the original amount of hours which is 6 plus 3 ones
Which is 6+1+1+1
In total, it will take 9 hrs for 45cm of snow to fall.