The car is 4 equal units. The train is 3⁄4 of the car = 3 of those units = $42.

Train$14$14$14Car$14$14$14$14$42

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

  1. Train = 3 units → $42
  2. 1 unit → $42 ÷ 3 = $14
  3. Car = 4 units → 4 × $14 = $56

The toy car cost $56.

Check: 3⁄4 of $56 = $42. ✓