Question Number 157972 by MathsFan last updated on 30/Oct/21
$$\:{given}\:\:\mathrm{2}{x}=\mathrm{3}{y}\:\:{and}\:\:\mathrm{4}{y}=\mathrm{3}{z} \\ $$$$\:{find}\:\:\:\frac{\mathrm{3}{x}−\mathrm{4}{y}}{\mathrm{2}{x}−{y}+\mathrm{5}{z}} \\ $$
Commented by tounghoungko last updated on 30/Oct/21
$${let}\:\mathrm{3}{y}={k}\Rightarrow{y}=\frac{{k}}{\mathrm{3}}\:\wedge\:\mathrm{2}{x}={k}\Rightarrow{x}=\frac{{k}}{\mathrm{2}} \\ $$$$\Rightarrow{z}=\frac{\mathrm{4}{k}}{\mathrm{9}} \\ $$$$\frac{\frac{\mathrm{3}{k}}{\mathrm{2}}−\frac{\mathrm{4}{k}}{\mathrm{3}}}{{k}−\frac{{k}}{\mathrm{3}}+\frac{\mathrm{20}{k}}{\mathrm{9}}}\:=\:\frac{\frac{\mathrm{3}}{\mathrm{2}}−\frac{\mathrm{4}}{\mathrm{3}}}{\frac{\mathrm{2}}{\mathrm{3}}+\frac{\mathrm{20}}{\mathrm{9}}}\:=\:\frac{\frac{\mathrm{1}}{\mathrm{6}}}{\frac{\mathrm{26}}{\mathrm{9}}}\:=\:\frac{\mathrm{1}}{\mathrm{6}}×\frac{\mathrm{9}}{\mathrm{26}}=\frac{\mathrm{3}}{\mathrm{52}} \\ $$
Commented by MathsFan last updated on 30/Oct/21
$${thanks}\:{sir} \\ $$
Commented by MathsFan last updated on 30/Oct/21
$${sir},\:{how}\:{did}\:{you}\:{get}\:\:{z}=\frac{\mathrm{4}{k}}{\mathrm{3}} \\ $$
Commented by Rasheed.Sindhi last updated on 30/Oct/21
$${z}=\frac{\mathrm{4}}{\mathrm{3}}{y}\Rightarrow{z}=\frac{\mathrm{4}}{\mathrm{3}}×\frac{{k}}{\mathrm{3}}=\frac{\mathrm{4}{k}}{\mathrm{9}} \\ $$
Commented by MathsFan last updated on 30/Oct/21
$${yeah} \\ $$$${thanks} \\ $$
Commented by tounghoungko last updated on 30/Oct/21
$${given}\:{codition}\:\mathrm{3}{z}=\mathrm{4}{y}\:{and}\:\mathrm{3}{y}={k}\:{or}\:{y}=\frac{{k}}{\mathrm{3}} \\ $$$${so}\:{z}=\frac{\mathrm{4}{y}}{\mathrm{3}}=\frac{\mathrm{4}}{\mathrm{3}}×\frac{{k}}{\mathrm{3}}=\frac{\mathrm{4}{k}}{\mathrm{9}} \\ $$
Answered by Rasheed.Sindhi last updated on 30/Oct/21
$$\mathrm{2}{x}=\mathrm{3}{y}\:\:{and}\:\:\mathrm{4}{y}=\mathrm{3}{z};\:\:\frac{\mathrm{3}{x}−\mathrm{4}{y}}{\mathrm{2}{x}−{y}+\mathrm{5}{z}}=? \\ $$$$\mathrm{2}{x}=\mathrm{3}{y}\Rightarrow\frac{{x}}{{y}}=\frac{\mathrm{3}}{\mathrm{2}} \\ $$$$\mathrm{4}{y}=\mathrm{3}{z}\Rightarrow\frac{{z}}{{y}}=\frac{\mathrm{4}}{\mathrm{3}} \\ $$$$\:\frac{\mathrm{3}{x}−\mathrm{4}{y}}{\mathrm{2}{x}−{y}+\mathrm{5}{z}}=\frac{\mathrm{3}\left(\frac{{x}}{{y}}\right)−\mathrm{4}}{\mathrm{2}\left(\frac{{x}}{{y}}\right)−\mathrm{1}+\mathrm{5}\left(\frac{{z}}{{y}}\right)} \\ $$$$\:\:\:\:\:=\frac{\mathrm{3}\left(\frac{\mathrm{3}}{\mathrm{2}}\right)−\mathrm{4}}{\mathrm{2}\left(\frac{\mathrm{3}}{\mathrm{2}}\right)−\mathrm{1}+\mathrm{5}\left(\frac{\mathrm{4}}{\mathrm{3}}\right)}=\frac{\:\:\frac{\mathrm{9}−\mathrm{8}}{\mathrm{2}}\:\:}{\frac{\mathrm{18}−\mathrm{6}+\mathrm{40}}{\mathrm{6}}} \\ $$$$\:\:\:\:\:=\frac{\mathrm{1}}{\cancel{\underset{\mathrm{1}} {\mathrm{2}}}}×\frac{\cancel{\overset{\mathrm{3}} {\mathrm{6}}}}{\mathrm{52}}=\frac{\mathrm{3}}{\mathrm{52}} \\ $$
Commented by MathsFan last updated on 30/Oct/21
$${thanks}\:{sir} \\ $$