In an exam, a student scores 30% of the total marks and

Solution

Let total marks = M Let pass marks = P First student: 30% of M = P − 30 (30/100)M = P − 30 …(1) Second student: 42% of M = P + 18 (42/100)M = P + 18 …(2) Subtract (1) from (2): (42/100 − 30/100)M = (P + 18) − (P − 30) (12/100)M = 48 M/ (100/12) = 48 → (12/100)M = 48 → M = 48 × 100/12 = 48 × 25/3? Wait: 48 × 100 / 12 = (48/12) × 100 = 4 × 100 = 400 So M = 400 Now from (1): (30/100) × 400 = P − 30 120 = P − 30 P = 150 Answer: Pass marks = 150.