Finding the Third Proportional to 139.50 and 300

Step by Step Solution

1. Step 1: Write the proportion equation
   139.50 : 300 = 300 : x
2. Step 2: Convert to fraction form
   139.50/300 = 300/x
3. Step 3: Cross multiply
   139.50x = 300 × 300
4. Step 4: Simplify right side
   139.50x = 90,000
5. Step 5: Solve for x
   x = 90,000/139.50
6. Step 6: Final answer
   x = 645.16