How does a person know whether to add/ subtract or multiply/divide first?
You answer this question using the rules of operations: PEMDAS.
Will the water levels in a glass containing ice and liquid water rise or lower?
Water levels will rise because the melted ice's liquid will take the place of the ice crystals.
What does the variable represent?
Solving for the variable is similar to find the missing piece of a puzzle. Rearrange the other pieces before the variable's meaning is known.