Answer: 1967
Step-by-step explanation:
Ada was 15 years when her sister Ngozi was 18 years.
This means that Ngozi is older than Ada by:
= 18 - 15
= 3 years
If Ngozi is older by 3 years, this means that she must have been born 3 years earlier than Ada
If Ada was born in 1970, Ngozi was born:
= 1970 - 3
= 1967
