Answer:
How many cuts are needed to cut the log into 5 equal pieces. 
 
Hopefully you figure out that it takes 4 cuts. 
 
Now if it takes 20 minutes in total then each cut would take how long. 
 
Divide the total time by number of cuts. 
 
So each cut takes 5 minutes. 
 
Now figure out how many cuts are needed to get ten equal pieces and multiply by 5 minutes 
 
Explanation: