What you will need is some 1/8″ thick 2″x1″ aluminum angle stock cut into pieces approximately 1.5″ wide. The short side will attach to the 80/20 profile in back and the long side should protrude forward and reach toward the back of the drawer slide.
Drill the short side first such that the long side is flush with the edge of the 80/20. For 10 series this will be directly in the middle of the 1″ side, and for 15 series this will be pulled towards the outer edge. Next, line up the long side of the aluminum bracket with any one of the pre-drilled holes on the drawer slide. Drill a 5/16″ hole through the aluminum and widen the pre-drilled hole in the drawer slide to 1/4″. both these two elements together with a 1/4″-20 bolt and a nylock nut. 3/4″ is the ideal length, but up to 1″ also works.