Finding the Fourth Proportional to 85.59, 128.34 and 42.23

Step by Step Solution

1. Step 1: Write the proportion equation
   85.59 : 128.34 = 42.23 : x
2. Step 2: Convert to fraction form
   85.59/128.34 = 42.23/x
3. Step 3: Cross multiply
   85.59x = 128.34 × 42.23
4. Step 4: Simplify right side
   85.59x = 5,420.12
5. Step 5: Solve for x
   x = 5,420.12/85.59
6. Step 6: Final answer
   x = 63.33