Finding the Fourth Proportional to 102,128.57, 140,935.39 and 56,805.57

Step by Step Solution

1. Step 1: Write the proportion equation
   102,128.57 : 140,935.39 = 56,805.57 : x
2. Step 2: Convert to fraction form
   102,128.57/140,935.39 = 56,805.57/x
3. Step 3: Cross multiply
   102,128.57x = 140,935.39 × 56,805.57
4. Step 4: Simplify right side
   102,128.57x = 8,005,915,162.12
5. Step 5: Solve for x
   x = 8,005,915,162.12/102,128.57
6. Step 6: Final answer
   x = 78,390.55