Answer:
18
Explanation:
The ratio of their ages was 5:3.
5 would be Chioma's age (because its greater) and 3 would be Chidi's age.
However, they are only 2 spaces apart and not 5, so keep adding multiples of the numbers until it gets to 5.
5:3
10:6
15:9
20:15
20:15 is the first one that was 5 years apart, so those must've been their ages three years ago.
Chidi would've been 15 years old, so adding 3 years to it to get to the present age, Chidi would be 18.