Finding the Fourth Proportional to 123,679.32, 185,415.09 and 86,128.53

Step by Step Solution

1. Step 1: Write the proportion equation
   123,679.32 : 185,415.09 = 86,128.53 : x
2. Step 2: Convert to fraction form
   123,679.32/185,415.09 = 86,128.53/x
3. Step 3: Cross multiply
   123,679.32x = 185,415.09 × 86,128.53
4. Step 4: Simplify right side
   123,679.32x = 15,969,529,141.52
5. Step 5: Solve for x
   x = 15,969,529,141.52/123,679.32
6. Step 6: Final answer
   x = 129,120.45