1. Department of Applied Science and Social Studies, Arusha Technical College, P. O. Box 296, Arusha, Tanzania
2. Department of Mathematics and Statistics, The University of Dodoma, P. O. Box 338, Dodoma, Tanzania
3. Department of Computer Science and Artificial Intelligence (Mathematics), SR University, Warangal 506371, Telangana, India
4. Department of Mathematics, Bowen University, Iwo, Nigeria