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 the number of islands visited be x and that peninsulas be y
thus,
x+y=19
⇒y=19-x.........i
if he skydives twice in islands and thrice in peninsulas, then the total number of skydives will be:
2x+3y=45.....ii

substituting i in ii we get:
2x+3(19-x)=45
2x+57-3x=45
putting like terms together we get:
2x-3x=45-57
-x=-12
therefore
x=12
and
y=19-x=19-12=7
hence the number of islands visited was 12 and that of peninsulas was 7