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If 9x + 7y = 130, 2x – y = 11, then what will be the value of (x + y)?1. 152. 143. 214. 16 |
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Answer» Correct Answer - Option 4 : 16 Given: 9x + 7y = 130 2x – y = 11 Calculation: Our given equation are 9x + 7y = 130 ----(1) 2x – y = 11 ----(2) Multiply eq (2) with 7 and equation (1) with 1 9x + 7y = 130 ----(3) 7(2x – y) = 11 × 7 = 77 ----(4) Add equation (4) and equation (3) 9x + 7y + 14x – 7y = 130 + 77 ⇒ 23x = 207 ⇒ x = 207/23 = 9 Now, from eq (2) 2x – y = 11 ⇒ 2 × 9 – y = 11 ⇒ y = 18 – 11 = 7 Now, x + y = 9 + 7 = 16 ∴ The required answer is 16 |
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