Finding the Fourth Proportional to 139,266.42, 208,695.51 and 86,515.98

Step by Step Solution

1. Step 1: Write the proportion equation
   139,266.42 : 208,695.51 = 86,515.98 : x
2. Step 2: Convert to fraction form
   139,266.42/208,695.51 = 86,515.98/x
3. Step 3: Cross multiply
   139,266.42x = 208,695.51 × 86,515.98
4. Step 4: Simplify right side
   139,266.42x = 18,055,496,569.25
5. Step 5: Solve for x
   x = 18,055,496,569.25/139,266.42
6. Step 6: Final answer
   x = 129,647.17