Finding the Fourth Proportional to 85.67, 128.50 and 42.35

Step by Step Solution

1. Step 1: Write the proportion equation
   85.67 : 128.50 = 42.35 : x
2. Step 2: Convert to fraction form
   85.67/128.50 = 42.35/x
3. Step 3: Cross multiply
   85.67x = 128.50 × 42.35
4. Step 4: Simplify right side
   85.67x = 5,441.76
5. Step 5: Solve for x
   x = 5,441.76/85.67
6. Step 6: Final answer
   x = 63.52