Finding the Fourth Proportional to 128,665.34, 177,625.38 and 99,920.51

Step by Step Solution

1. Step 1: Write the proportion equation
   128,665.34 : 177,625.38 = 99,920.51 : x
2. Step 2: Convert to fraction form
   128,665.34/177,625.38 = 99,920.51/x
3. Step 3: Cross multiply
   128,665.34x = 177,625.38 × 99,920.51
4. Step 4: Simplify right side
   128,665.34x = 17,748,418,558.54
5. Step 5: Solve for x
   x = 17,748,418,558.54/128,665.34
6. Step 6: Final answer
   x = 137,942.50