Let us assume Toni made 100 apple pies in 10 hours, that means 10/hour.
Now, with help of assistant she produces 60% more and work for 20% less time.
So,
[100+(60% of 100)] = 160 apple pies produced in [10-(20% of 10)]= 8 hours.
160/8 = 20/hour
So, with the help of assistant Toni's output of apple pies per hour increases by 100%.