Question

Solve 6x = 7y and 3x + 9y = 15 by substitution method

Answer 1

$\sf{6x = 7y ---(i)}$

$\sf{\implies x = \frac{7y}{6} ---(ii)}$

$\sf{\implies 3x + 9y = 15 }$

substitute the value of x form (ii)

$\sf{\implies 3( \frac{7y}{6} ) + 9y = 15 }$

$\sf{\implies \frac{7y}{2} + 9y = 15}$

$\sf{\implies 7y + 18y = 30}$

$\sf{\implies 25y=30}$

$\boxed{\bf{\therefore y=\frac{6}{5}}}$

substitute value of y in (i)

$\sf{\implies \cancel{6}x=7(\frac{\cancel{6}}{5})}$

$\boxed{\bf{\therefore x = \frac{7}{5}}}$

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