Maybe is an equation, they are like "2x-5=34"
If it so, then the way to resolve it would be adding the five (if the symbol is a minus) in both sides ( under the five and under the 34, then eliminate the "-5" and is going to be "2x=38") Then divide 2 in both sides (2/2 and 38/2) and is going to be (x=19)
BUT if it's not the type of question you are referring about then idk how to help you because i don't have any details (?)