Difficulty: Easy
Correct Answer: 120
Explanation:
Introduction: This is a fractional linear equation in a single variable. We will convert each verbal fraction into an algebraic expression in terms of the unknown number and solve.
Given Data / Assumptions:
Concept / Approach: Bring all N-terms to one side to isolate the net fraction of N equal to 34. Use a common denominator to combine terms exactly.
Step-by-Step Solution:
(1/3 + 1/4 + 1/5 − 1/2)N = 34.Common denominator 60: (20 + 15 + 12 − 30)/60 = 17/60.(17/60)N = 34 → N = 34 * 60 / 17 = 120.Verification / Alternative check: Compute both sides with N = 120: LHS partials = 40 + 30 + 24 = 94; half of N = 60; 94 exceeds 60 by 34, correct.
Why Other Options Are Wrong: 60, 30, 90 do not satisfy the equation; “None of these” is unnecessary because a valid integer solution exists.
Common Pitfalls: Arithmetic with fractions, especially signs when moving 1/2N to the left; ensure exact common denominator.
Final Answer: 120
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