Paulo is 6 years older than her sister. In 10 years, the sum of their ages be 50. Find their present ages.

Answer 1

Now:
sister's age --- x
Paulo's age --- x+6

10 years from now:
sister's age = x+10
Paulo's age = x+6 + 10 = x+16

x+6 + x+16 = 50

carry on...