The ratio of the ages of two friends is 7 : 9. After 10 years, it will be 19 : 23. What will be the average age after 7 years from now?

39 years

ATQ,

Let ages of two friends be 7x and 9x

After 10 years \(\frac{7x + 10}{9x + 10}\) = \(\frac{19}{23}\)

                      ⇒ 161x + 230 = 171x + 190

                      ⇒ 10x = 40

                          x = 4

After 7 years their ages will be 35 and 43

Average of age after 7 years = 39 years