Ex-3.2 Q-1

Let number of boys who took part in the quiz = x Let number of girls who took part in the quiz = y According to given conditions, we have x + y = 10… (1) And, y = x + 4 ⇒ x – y = −4 … (2) For equation x + y = 10, we have following points which lie on the line For equation x – y = –4, we have following points which lie on the line We plot the points for both of the equations to find the solution. We can clearly see that the intersection point of two lines is (3, 7). Therefore, number of boys who took park in the quiz = 3 and, number of girls who took part in the quiz = 7. (ii) Let cost of one pencil = Rs x and Let cost of one pen = Rs y According to given conditions, we have 5x + 7y = 50… (1) 7x + 5y = 46… (2) For equation 5x + 7y = 50, we have following points which lie on the line For equation 7x + 5y = 46, we have following points which lie on the line We can clearly see that the intersection point of two lines is (3, 5). Therefore, cost of pencil = Rs 3 and, cost of pen = Rs 5

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