\(\dfrac{x}{y}=10\)
=>\(x=10\cdot y=10y\)
\(M=\dfrac{16x^2-40xy}{8x^2-24xy}\)
\(=\dfrac{8x\cdot2x-8x\cdot5y}{8x\cdot x-8x\cdot3y}\)
\(=\dfrac{8x\left(2x-5y\right)}{8x\left(x-3y\right)}=\dfrac{2x-5y}{x-3y}\)
\(=\dfrac{2\cdot10y-5y}{10y-3y}=\dfrac{20-5}{10-3}=\dfrac{15}{7}\)





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