Finding the Fourth Proportional to 139,688.84, 209,199.74 and 80,399.88

Step by Step Solution

1. Step 1: Write the proportion equation
   139,688.84 : 209,199.74 = 80,399.88 : x
2. Step 2: Convert to fraction form
   139,688.84/209,199.74 = 80,399.88/x
3. Step 3: Cross multiply
   139,688.84x = 209,199.74 × 80,399.88
4. Step 4: Simplify right side
   139,688.84x = 16,819,633,590.03
5. Step 5: Solve for x
   x = 16,819,633,590.03/139,688.84
6. Step 6: Final answer
   x = 120,407.86