How do you use a number line to solve 245-137 i thought i told a boy about that today but here it goes again you start from 0 to 245 and count back 137 and if you dont understand the concept of a number line here it goes a number line is a horizontal line going straight across with vertical lines going down hope that helps and if you still dont understand try this google a number line in images that should work your welcome!!!!!!!!!!!!!!!!!!!!!