Question

dacă x/y=5/9 calculați 5x-4y/4x-5y dau 20pct​

Answer 1

x=5k
y=9k
Înlocuim și vom avea
(5*5k-4*9k)/(4*5k-5*9k)
(25k-36k)/(20k-45k)=
-11k/-25k=
11/25

Answer 2

$\it \dfrac{x}{y}=\dfrac{5}{9} \Rightarrow \dfrac{y}{x}=\dfrac{9}{5} \Rightarrow \dfrac{y}{x}=1,8 \Rightarrow y=1,8x\ \ \ \ \ \ (*)\\ \\ \\ \dfrac{5x-4y}{4x-5y}\ \stackrel{(*)}{=}\ \dfrac{5x-4\cdot1,8x}{4x-5\cdot1,8x}=\dfrac{5x-7,2x}{4x-9x}=\dfrac{-2,2x}{-5x}=\dfrac{2,2}{5}=0,44$