Finding the Fourth Proportional to 105.86, 158.54 and 80.12

Step by Step Solution

1. Step 1: Write the proportion equation
   105.86 : 158.54 = 80.12 : x
2. Step 2: Convert to fraction form
   105.86/158.54 = 80.12/x
3. Step 3: Cross multiply
   105.86x = 158.54 × 80.12
4. Step 4: Simplify right side
   105.86x = 12,702.22
5. Step 5: Solve for x
   x = 12,702.22/105.86
6. Step 6: Final answer
   x = 119.99