Finding the Fourth Proportional to 139,123.80, 208,090.14 and 129,039.30

Step by Step Solution

1. Step 1: Write the proportion equation
   139,123.80 : 208,090.14 = 129,039.30 : x
2. Step 2: Convert to fraction form
   139,123.80/208,090.14 = 129,039.30/x
3. Step 3: Cross multiply
   139,123.80x = 208,090.14 × 129,039.30
4. Step 4: Simplify right side
   139,123.80x = 26,851,806,002.50
5. Step 5: Solve for x
   x = 26,851,806,002.50/139,123.80
6. Step 6: Final answer
   x = 193,006.56