Finding the Fourth Proportional to 85,670.70, 128,464.42 and 42,957.78

Step by Step Solution

1. Step 1: Write the proportion equation
   85,670.70 : 128,464.42 = 42,957.78 : x
2. Step 2: Convert to fraction form
   85,670.70/128,464.42 = 42,957.78/x
3. Step 3: Cross multiply
   85,670.70x = 128,464.42 × 42,957.78
4. Step 4: Simplify right side
   85,670.70x = 5,518,545,904.42
5. Step 5: Solve for x
   x = 5,518,545,904.42/85,670.70
6. Step 6: Final answer
   x = 64,415.79