Finding the Fourth Proportional to 139,937.76, 209,780.16 and 51,128.64

Step by Step Solution

1. Step 1: Write the proportion equation
   139,937.76 : 209,780.16 = 51,128.64 : x
2. Step 2: Convert to fraction form
   139,937.76/209,780.16 = 51,128.64/x
3. Step 3: Cross multiply
   139,937.76x = 209,780.16 × 51,128.64
4. Step 4: Simplify right side
   139,937.76x = 10,725,774,279.78
5. Step 5: Solve for x
   x = 10,725,774,279.78/139,937.76
6. Step 6: Final answer
   x = 76,646.75