The current average age of a couple and their daughter is 35 years. After 15 years, the mother's age will equal the combined current ages of the father and the daughter. What is the mother's present age?

Explanation

Let the father's, mother's, and daughter's present ages be f, m, and d respectively. Given the average age is 35, so (f + m + d) / 3 = 35, which implies f + m + d = 105. After 15 years, the mother's age will be m + 15, and this equals the sum of the current ages of the father and daughter: f + d. Substituting f + d = m + 15 into the sum equation gives m + (m + 15) = 105, or 2m + 15 = 105. Solving for m, we get 2m = 90, so m = 45 years.