Finding the Fourth Proportional to 30,756.12, 42,450.33 and 20,139.57

Step by Step Solution

1. Step 1: Write the proportion equation
   30,756.12 : 42,450.33 = 20,139.57 : x
2. Step 2: Convert to fraction form
   30,756.12/42,450.33 = 20,139.57/x
3. Step 3: Cross multiply
   30,756.12x = 42,450.33 × 20,139.57
4. Step 4: Simplify right side
   30,756.12x = 854,931,392.56
5. Step 5: Solve for x
   x = 854,931,392.56/30,756.12
6. Step 6: Final answer
   x = 27,797.11