Finding the Fourth Proportional to 42,856.50, 64,326.32 and 20,685.50

Step by Step Solution

1. Step 1: Write the proportion equation
   42,856.50 : 64,326.32 = 20,685.50 : x
2. Step 2: Convert to fraction form
   42,856.50/64,326.32 = 20,685.50/x
3. Step 3: Cross multiply
   42,856.50x = 64,326.32 × 20,685.50
4. Step 4: Simplify right side
   42,856.50x = 1,330,621,667.30
5. Step 5: Solve for x
   x = 1,330,621,667.30/42,856.50
6. Step 6: Final answer
   x = 31,048.30