Ta có: \(y-x=4\Rightarrow y=4+x\)
\(\dfrac{x-5}{y-7}=\dfrac{5}{7}\Rightarrow\dfrac{x-5}{x+4-7}=\dfrac{5}{7}\Rightarrow\dfrac{x-5}{x-3}=\dfrac{5}{7}\)
\(\Rightarrow7x-35=5x-15\)
\(\Rightarrow2x=20\)
\(\Rightarrow x=10\)
\(\Rightarrow y=14\)
\(\Rightarrow x+y=24\)
Vậy x + y = 24
Ta có:
\(7\left(x-5\right)=5\left(y-7\right)\)
\(7x-35=5y-35\)
\(7x=5y\)
\(\dfrac{x}{y}=\dfrac{5}{7}\)
số x là:
4:(7-5)x5=10
số y là:
y=10+4=14