The average of 2 masses means the total is 2 × 37.5 = 75 kg (worked out from the given 37.5). Mike = 1 unit, Calvin = 2 units.

Mike1Calvin11total = 2 × 37.5 = 75 kg

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

  1. Total mass → 2 × 37.5 = 75 kg
  2. Mike + Calvin = 3 units → 75 kg
  3. 1 unit → 75 ÷ 3 = 25 kg
  4. Calvin = 2 units → 2 × 25 = 50 kg

Calvin’s mass is 50 kg.

Check: (25 + 50) ÷ 2 = 37.5 kg. ✓