The situation can be sketched in the following diagram.
The angles are in the following order
68 > 67 > 45.
Here are some facts about the relationship between angles and triangles:
The shortest side is always opposite the smallest angle.
The longest side is always opposite the largest angle.
Hence, the smallest side is that of the Clarinet and the longest side is that of the trumpet; therefore, the sides ordered from least to greatest are
Clarinet, Flute, Trumpet.