Let x = the number of guitars Steve has.
Barbeck has 2x guitars, and Davey has 3 * 2x = 6x guitars.
2x + 6x + x = 27
9x = 27
x = 27 / 9 = <<27/9=3>>3 so Steve has 3 guitars.
Barbeck has 2 * 3 = <<2*3=6>>6 guitars.
And Davey has 3 * 6 = <<3*6=18>>18 guitars.
#### 18