Answer:
44%
Explanation:
Suppose the original number is 100. 
 It is increased by 20 %, so the result will be 120. 
The resulting number is again increased by 20%, which is increased by 120 *20/100, which is increased by 24. The final result will be 120+24 that is 144. 
The final result is increased by 44 compared to the original number 100. 
So, increase by 44%.