# Merging properties

Occasionally, properties may merge together. This is unlikely to occur when working with simple equations, but it may happen more frequently with larger and more complex equations.

Suppose you created the following expression, setting x to green and y to red:

After creating this expression, you realized you didn't mean to type x + y; what you really meant was the single variable xy. Your natural impulse would be to remove the plus sign between the two. However, if you do this and try to make them into a single variable, then what color wins? A single variable can only have one color, and we've got two from which to choose.

The answer is that the property of the element on the right is the one that wins. In this case, removing the plus sign gives us:

This situation occurs regardless of what properties are set. If the above example had no color set on y, then when the plus sign was removed, both x and y would revert to the default color — black. More correctly, they would both assume the inherited color, whatever that was. If a color other than black had been set on a higher branch in the expression tree, they would assume this color.