Turn left into Schofield Barracks McNair Gate. After passing the sentry, make an immediate right onto Ayres Avenue. Hale Kula Elementary School is on the left. *If you do not have a military base pass, you will need to enter through Lyman Gate (see map).
There are 12 possible keys any particular song can be played in. This is because of the 12 notes on the piano keyboard, A, A#/Bb, B, C, C#/Db, D, D#/Eb, E, F, F#/Gb, G, and G#/Ab. A song can be played so that any one of these twelve notes will be the tonal center or home base.
If your piano music is written in the key of G (with the F#) and you encounter an F#, you have two transposing choices, G# or Ab. Since your trumpet will be playing in the key of A (the key a whole-step above G), you will write G# because it belongs to that key.