Finding the Fourth Proportional to 139,978.88, 209,864.64 and 84,561.92

Step by Step Solution

1. Step 1: Write the proportion equation
   139,978.88 : 209,864.64 = 84,561.92 : x
2. Step 2: Convert to fraction form
   139,978.88/209,864.64 = 84,561.92/x
3. Step 3: Cross multiply
   139,978.88x = 209,864.64 × 84,561.92
4. Step 4: Simplify right side
   139,978.88x = 17,746,556,898.51
5. Step 5: Solve for x
   x = 17,746,556,898.51/139,978.88
6. Step 6: Final answer
   x = 126,780.25