A sum of money doubles in 20 years on simple interest. It will triple at the same rate in _?

A. 40

B. 60

C. 50

D. 80

The said problem, to find the year where as the money would be triple if it would be double in 20 years. So base on that, the best answer would be in letter A. 40. I hope you are satisfied with my answer and feel free to ask for more if you have questions and further clarifications