Finding the Fourth Proportional to 105.42, 145.17 and 85.98

Step by Step Solution

1. Step 1: Write the proportion equation
   105.42 : 145.17 = 85.98 : x
2. Step 2: Convert to fraction form
   105.42/145.17 = 85.98/x
3. Step 3: Cross multiply
   105.42x = 145.17 × 85.98
4. Step 4: Simplify right side
   105.42x = 12,481.72
5. Step 5: Solve for x
   x = 12,481.72/105.42
6. Step 6: Final answer
   x = 118.40