Watch the Level 3: Blues Chord Melody online guitar lesson by Jason Loughlin from Take 5: Blues Chord Melody
This etude is over a 12 bar blues in A. In the last four bars, we're playing the V chord for the first two bars. There is no V-IV progression in the last four. The turnaround is I-IV-I-V. We're using an augmented chord for or V chord. To recap, the last four bars are V|V|I-IV|I-V|.