Q. In a class test, the sum of Shefali’s marks in Mathematics and English is 30. Had she got 2 marks more in Mathematics and 3 marks less in English, the product of their marks would have been 210. Find her marks in the two subjects.

Ans:  Let’s consider the marks in mathematics be X.

Hence, her marks in English = 30 – X (by given condition) …. (i)

Next, according to 2nd condition: marks in maths = X + 2, marks in English = (30 – X – 3)

by given condition: product of their marks would have been 210

\therefore (X + 2) (30 - X - 3) = 210

\therefore (X + 2) (27 - X) = 210

\therefore - X^2 + 27 X - 2 X + 54 = 210

\therefore X^2 - 25 X + 156 = 0

therefore X^2 - 13 X - 12 X + 156 = 0

therefore (X - 13) (X - 12) = 0

Therefore, X = 13 and X = 12

by equation (i), when X = 13, (30 – X) = 17 and when X = 12, (30 – X) = 18

Therefore, when Shefali got 13 marks in Mathematics, she scored 17 marks in English and when Shefali got 12 marks in Mathematics, she scored 18 marks in English.

Therefore, her marks in Mathematics and English are 13 and 17 respectively or 12 and 18 respectively. The question will have 2 answers.

Check:

Case 1: marks in Maths and English: 13 and 17:

New marks: Maths = 13 + 2 = 15, English = 17 – 3 = 14. Since 15 x 14 = 210, hence our answer is correct.

Case 2: marks in Maths and English: 12 and 18:

New marks: Maths = 12 + 2 = 14, English = 18 – 3 = 15. Since 14 x 15 = 210, hence our answer is correct.

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