Finding the Fourth Proportional to 139,761.40, 209,728.50 and 56,656.12

Step by Step Solution

1. Step 1: Write the proportion equation
   139,761.40 : 209,728.50 = 56,656.12 : x
2. Step 2: Convert to fraction form
   139,761.40/209,728.50 = 56,656.12/x
3. Step 3: Cross multiply
   139,761.40x = 209,728.50 × 56,656.12
4. Step 4: Simplify right side
   139,761.40x = 11,882,403,063.42
5. Step 5: Solve for x
   x = 11,882,403,063.42/139,761.40
6. Step 6: Final answer
   x = 85,019.20