When maras math project was graded, her teacher gave her 40 points for showing all of her calculations. She
then deducted 15 points for not following
instructions, gave 20 points for a parent
signature, and reduced her final grade by
30 points for being late. Which
expression would help Mara calculate the
final grade on her project?
A. (-20) + (-40)+ 15 + 30
B. 20 + 40 + 15 + 30
C. 40 + (-20) + (-30) + 15
D. 40 + (-15) + 20 + (-30)