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Solve for x and y : 3x +… (Class 10 Maths Basic 2025, Q21b)

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MathsCBSE Class 10 · Basic · Board exam 2025, set 430/2/1 · 2 marks · Very short answer

CBSE Class 10 Mathematics Basic 2025: question 21(b)

Set in the CBSE Class 10 board exam of 2025, paper 430/2/1, section B, question 21(b), for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q21(b) · 2 marks · Very short answerPair of Linear Equations in Two Variables

Solve for x and y : ,

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 430/2/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

The coefficients are swapped between the two equations — try adding and subtracting them.

Hint 2

Adding gives x + y and subtracting gives x − y; now solve these simpler equations.

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

  1. Adding the equations: ...(i). Subtracting the second from the first: ...(ii).

  2. Adding (i) and (ii): .

    1 mark

  3. From (i): .

    1 mark

Answer: x = 15, y = 10

Where the marks are

  • Obtains (1 mark)
  • Obtains (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Pair of Linear Equations in Two Variables, one at a time, marked against the answer key and marking points.Back to the full paper2025 board paper, set 430/2/1 (Basic): every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.