Concept:Use the BODMAS rule: solve Brackets first, then Multiplication, then Addition and Subtraction from left to right.Explanation:First, solve the bracket: (21+18)=39.Then multiply: 39×2=78.Now the expression becomes: 77−41+34+78−55.Add all positive terms: 77+34+78=189.Add all negative terms: 41+55=96.Subtract: 189−96=93.Answer:93 (Option D)