Ronaldo's age = 13
after 5 years, his age = 13+5 = 18 years
After 5 years, Marissa's age = 18 * 2/3 = 12 years
Present age of marissa = 12 - 5 = 7 years
in 3 years, marissa's age = 7 + 3 = 10 years
Marissa will be 10 years old in 3 years.
Hope it helps!