Question

$3x + jy = 9 and 5x + 3y = 7 then what is then value of x + y$
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Answer 1

${\huge{\underline{\mathfrak{\blue {Solution}}}}}$

$3x + jy = 9 \: and \: 5x + 3y = 7 \\ {\implies{x + jy = \frac{9}{3} \: and \: x + y = \frac{7}{5 \times 3}}} \\ {\implies{x + jy = 3 \: and \: x + y = \frac{7}{15} }} \\ {\implies{\boxed{x + y = \frac{7}{15} }}} \\ \\ \\ x + jy = 3 \\ {\implies{x + y = 3 \div j}} \\ {\implies{ \frac{7}{15} = 9 \div j}} \\ {\implies{j = \frac{9 \times 15}{7} }} \\ {\implies{\boxed{j = \frac{135}{7} }}}$