Question

Mr. Tanaka is 35 years old, and his son is 5.  In how many years will Mr. Tanaka be exactly three times as old as his son?( show how you got your answer

Answer 1

10 years.

Explanation:

Present age of Mr. Tanaka = 35 years

Present age of his son = 5 years

Now let the number of years be x. As after x years both of their age will increased by x years, therefore

After x years age of Mr. Tanaka = 35 + x

After x years age of his son = 5 + x

According to question,

Mr.Tanaka's age after x years = 3 (His son's age after x years)

35 + x = 3 (5 + x)

Further solving,

35 + x = 15 + 3x

3x - x = 35 - 15

2x = 20

x = 10

Therefore after 10 years Mr. Tanaka's age will be exactly three times as old as his son. As after 10 years Mr. tanaka's age will be 45 and his son's age will be 15.