The three items together cost 3 × the average. Take out the skirt and blouse to leave the dress.

$19$14?total = 3 × $28 = $84skirtblousedress

Plain numbers are given; italic underlined numbers are worked out.

  1. Total of 3 items → 3 × $28 = $84
  2. Skirt + blouse → $19 + $14 = $33
  3. Dress → $84 − $33 = $51

The dress cost $51.

Check: ($19 + $14 + $51) ÷ 3 = $84 ÷ 3 = $28. ✓