Let their ages be m and t, respectively. Currently, m = 4t.
In ten years: t+10 = (1/2)(m+10).
Multiplying both sides by 2, we get 2t + 20 = m + 10. Substituting 4t for m produces
2t + 20 = 4t + 10. Then 10 = 2t, and t=5. Tamanna is currently 5 years old, and her mother is 20.