A cap is 1 unit and a shirt is 2 units. So 2 shirts = 4 units and 6 caps = 6 units — 10 units in all = $23.

2 shirts11116 caps111111$23

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

  1. 2 shirts + 6 caps = 4 + 6 = 10 units → $23
  2. 1 unit (cap) → $23 ÷ 10 = $2.30
  3. 1 shirt + 1 cap = 2 + 1 = 3 units → 3 × $2.30 = $6.90

A shirt and a cap together cost $6.90.

Check: shirt $4.60 + cap $2.30 = $6.90; 2(4.60) + 6(2.30) = $23. ✓