5+a4

The expression "5 + a4" suggests the addition of the number 5 and the term "a4," which could represent a variable, a number, or could be a typo. If "a4" is intended to represent a variable (like "a" multiplied by 4 or just a variable name), then the expression remains as "5 + a4."

If you meant something else by "a4," please clarify, and I can assist further! If you want to simplify or solve it, knowing the value of "a" would be necessary.