21.3 Stacked vs Unstacked.

Stacking of fractions (ie, separating numerator and denominator by a horizontal line) should be avoided in favor of “unstacking” (ie, using a slash in place of the horizontal line) unless this sacrifices clarity (see , Punctuation, Forward Slash [Virgule, Solidus], In Equations).y=(x1+x2)/(x1−x2) instead of y=x1+x2x1−x2Whenever a fraction is unstacked, parentheses, brackets, and braces (collectively called “fences” in mathematical notation) should be used as appropriate to avoid ambiguity. For instance, the expression a+b+cd+e,if written as a + b + c/d + e, is ambiguous and could have several interpretations, such as a+b+cd+e or a+b+cd+e.The expression’s meaning is unambiguous if set off as follows: ...Less