B can finish work 1 on his own in 20 days and work 2 in 18 days. A is 33.33% more efficient than B when it comes to work 1 and 40% less efficient than B when it comes to work 2. A completes work 1 in 10 days with the help of C, and in the same time, A also completes work 2 with the help of C. What is the difference in the time taken by C alone to complete work 1 and work 2?