Finding the Fourth Proportional to 139,629.78, 207,865.31 and 138,799.40

Step by Step Solution

1. Step 1: Write the proportion equation
   139,629.78 : 207,865.31 = 138,799.40 : x
2. Step 2: Convert to fraction form
   139,629.78/207,865.31 = 138,799.40/x
3. Step 3: Cross multiply
   139,629.78x = 207,865.31 × 138,799.40
4. Step 4: Simplify right side
   139,629.78x = 28,851,578,575.49
5. Step 5: Solve for x
   x = 28,851,578,575.49/139,629.78
6. Step 6: Final answer
   x = 206,629.12