Question no. 1(c)
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https://www.meritnation.com/ask-answer/question/how-to-solve-the-following-equation-by-substitution-method/pair-of-linear-equations-in-two-variables/9096371
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https://www.meritnation.com/ask-answer/question/how-to-solve-the-following-equation-by-substitution-method/pair-of-linear-equations-in-two-variables/9096371
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