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Question
Solve 0.4x + 0.3y = 1.7; 0.7 x − 0.2y = 0.8
Solution
0.4x + 0.3y = 1.7
∴ 4x + 3y = 17 ......(i)[Multiplying both sides by 10]
0.7x – 0.2y = 0.8
∴ 7x – 2y = 8 ......(ii)[Multiplying both sides by 10]
Multiplying equation (i) by 2, we get
8x + 6y = 34 ......(iii)
Multiplying equation (ii) by 3, we get
21x – 6y = 24 ......(iv)
Adding equations (iii) and (iv), we get
8x + 6y = 34
+21x – 6y = 24
29x = 58
∴ x = `58/29` = 2
Substituting x = 2 in equation (i), we get
4(2) + 3y = 17
∴ 8 + 3y = 17
∴ 3y = 9
∴ y = `9/3` = 3
∴ x = 2 and y = 3 is the solution of the equation 0.4x + 0.3y = 1.7 and 0.7x – 0.2y = 0.8.
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