Finding the Fourth Proportional to 85,600.80, 129,042.72 and 79,891.92

Step by Step Solution

1. Step 1: Write the proportion equation
   85,600.80 : 129,042.72 = 79,891.92 : x
2. Step 2: Convert to fraction form
   85,600.80/129,042.72 = 79,891.92/x
3. Step 3: Cross multiply
   85,600.80x = 129,042.72 × 79,891.92
4. Step 4: Simplify right side
   85,600.80x = 10,309,470,662.82
5. Step 5: Solve for x
   x = 10,309,470,662.82/85,600.80
6. Step 6: Final answer
   x = 120,436.62