Answer:
337
Explanation:
I remember this from UKMT maths challenge.
Let the number of kangaroos in each of the seven parks be , , , , , and with the
corresponding number of koalas being , , , , , and . The question tells us that the
number of kangaroos in any park is equal to the sum of the numbers of koalas in the other six
parks. Therefore we have
= + + + + + ,
= + + + + + ,
= + + + + + ,
= + + + + + ,
= + + + + + ,
= + + + + + ,
= + + + + + .
Adding these equations, we obtain
+ + + + + + = 6( + + + + + + ).
The total number of kangaroos in the seven parks is 2022. Hence
+ + + + + + = 2022.
Therefore
2022 = 6( + + + + + + )
and hence the total number of koalas in the seven parks is
+ + + + + + = 2022 ÷ 6 = 337.