Step 1: Start by understanding the units involved in the conversion. In this case, we are converting from centimeters (cm) to inches (in).

Step 2: Write down the given value, 20cm. This will be our starting value for the conversion.

Step 3: Recall the conversion factor between centimeters and inches, which is 2.54cm = 1in. This means that 2.54cm is equal to 1 inch, or in other words, 1cm is equal to 1/2.54 inches.

Step 4: Set up a proportion using the conversion factor. This will help us to solve for the unknown value, which is the equivalent measurement in inches. The proportion should look like this:

20cm/1 = xin/2.54cm

Step 5: Solve for the unknown value (xin) by cross-multiplying. This means multiplying 20 by 1, and then dividing the result by 2.54. The equation will look like this: xin = (20*1)/2.54 = 7.874 inches.

Step 6: Write down the final answer with the appropriate unit. In this case, our final answer is 7.874 inches. It is important to always include the correct unit in any measurement.

Step 7: Double check your answer by using a calculator or by using a conversion chart. Make sure that your answer is reasonable and accurate.

Step 8: You have successfully converted 20cm to inches! You can now confidently tell someone that 20cm is equal to 7.874 inches.