Melissa and Brian are at the base of a mountain. Melissa hikes to a location 27 meters above sea level. Brian hikes to a location 21 meters below sea level. Part A. [Already Done]

Part B. Write an expression to represent the difference of the hikers' altitudes. Evaluate your expression.

Part C. Can the integers be subtracted in either order to find the difference?

25 points for 2 questions, is that alright? Don't answer something random to get the points, ya'll are desperate.