Challenge Level

The number of bunches must divide the number of white roses, the number of yellow roses and the number of red roses.

The highest common factor of $24$, $36$ and $42$ is $6$, so the most bunches Flora can make is $6$, each consisting of $4$ white, $6$ yellow and $7$ red roses.

Use all the roses to make identical bunches - so all bunches will have the same ratio of colours as the total

$24:42:36$

$12:21:18$

$4:7:6$

Cannot simplify further so each bunch has $4$ white roses

So Flora can make $6$ from $24$ white roses

This problem is taken from the UKMT Mathematical Challenges.

You can find more short problems, arranged by curriculum topic, in our short problems collection.