For measuring 15cm Julio can go through following steps:
Step 1: Draw two lines of length 21.5cm one by one. So it is a line of length 21.5 + 21.5 = 43cm.
Step 2: Remove 28cm length line from end of first line. Thus it will give 43- 28 = 15cm line.
Hope that's clear, to learn more on Real Word Application of geometry, you may click the link below
http://www.winpossible.com/lessons/Geom ... tions.html