Three fewer trumpets than Miles has fingers is 10-3=<<10-3=7>>7 trumpets.
Two more guitars than he has hands is 2+2=<<2+2=4>>4 guitars.
Two more trombones than he has heads is 2+1=<<2+1=3>>3 trombones.
And one fewer French horn than he has guitars is 4-1=<<4-1=3>>3 French horns.
Altogether, Miles owns 7+4+3+3=<<7+4+3+3=17>>17 musical instruments.
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