Question

Ni Hua is an adventurous traveler. He skydives twice in every island he visits and skydives thrice in every peninsula he visits.
In the last decade, Ni Hua went skydiving a total of
\[45\] times in the
\[19\] islands and peninsulas that he visited.
How many islands and peninsulas did Ni Hua visit?

Answer 1

Let I be the number of islands and P the number of peninsulas. Then
I + P = 19 and 2I + 3P = 45.
From the first, I = 19 − P. Substitute: 2(19 − P) + 3P = 45 → 38 + P = 45 → P = 7.
So I = 19 − 7 = 12.

Ni Hua visited 12 islands and 7 peninsulas.