Finding the Fourth Proportional to 42,856.61, 64,326.36 and 20,685.59

Step by Step Solution

1. Step 1: Write the proportion equation
   42,856.61 : 64,326.36 = 20,685.59 : x
2. Step 2: Convert to fraction form
   42,856.61/64,326.36 = 20,685.59/x
3. Step 3: Cross multiply
   42,856.61x = 64,326.36 × 20,685.59
4. Step 4: Simplify right side
   42,856.61x = 1,330,628,387.52
5. Step 5: Solve for x
   x = 1,330,628,387.52/42,856.61
6. Step 6: Final answer
   x = 31,048.39