Height of the pole (x)=15 m
Climbed distance per minute (y)=4 m
Slips(y)= 2 m in next minute
So, in 2 minutes , he climbs 2 m
We take, 2 meters= 1 unit of time
time =2 minutes
You can calculate time by this formula:
Reqd. time=[(height of pole - slipped distance )/ (climbed distance -slipped distance )]*t
At last, the monkey will climb 1 m in 45 seconds because once he got up he never slipped.
So, total time=12 minutes 45 seconds.