T=trumpet students; F=flute students; G=guitar students.
Draw a number line with T about the middle. To the left of T means less or fewer than T, and to the right means more or greater than T. So mark F to the left of T and G to the right: F<T<G.
If you write F<G and T<G, then you can't tell the relationship between T and F because F<T<G and T<F<G both fit the conditions.
I hope this what you mean by changing the bar.