Finding the Fourth Proportional to 139,128.32, 208,521.45 and 64,144.38

Step by Step Solution

1. Step 1: Write the proportion equation
   139,128.32 : 208,521.45 = 64,144.38 : x
2. Step 2: Convert to fraction form
   139,128.32/208,521.45 = 64,144.38/x
3. Step 3: Cross multiply
   139,128.32x = 208,521.45 × 64,144.38
4. Step 4: Simplify right side
   139,128.32x = 13,375,479,126.95
5. Step 5: Solve for x
   x = 13,375,479,126.95/139,128.32
6. Step 6: Final answer
   x = 96,137.72