Finding the Fourth Proportional to 105,513.60, 145,641.60 and 86,851.20

Step by Step Solution

1. Step 1: Write the proportion equation
   105,513.60 : 145,641.60 = 86,851.20 : x
2. Step 2: Convert to fraction form
   105,513.60/145,641.60 = 86,851.20/x
3. Step 3: Cross multiply
   105,513.60x = 145,641.60 × 86,851.20
4. Step 4: Simplify right side
   105,513.60x = 12,649,147,729.92
5. Step 5: Solve for x
   x = 12,649,147,729.92/105,513.60
6. Step 6: Final answer
   x = 119,881.68