Finding the Fourth Proportional to 139.56, 209.38 and 42.06

Step by Step Solution

1. Step 1: Write the proportion equation
   139.56 : 209.38 = 42.06 : x
2. Step 2: Convert to fraction form
   139.56/209.38 = 42.06/x
3. Step 3: Cross multiply
   139.56x = 209.38 × 42.06
4. Step 4: Simplify right side
   139.56x = 8,806.63
5. Step 5: Solve for x
   x = 8,806.63/139.56
6. Step 6: Final answer
   x = 63.10