Question

A,\(\dfrac{1,2}{30}\)=\(\dfrac{3x+4}{50}\)

B,\(\dfrac{3}{x-1}\)=\(\dfrac{21}{16}\)

D,\(\dfrac{x}{5}\)=\(\dfrac{y}{2}\) và 3x - 2y =44

Answer 1

\(\Leftrightarrow1,2.50=\left(3x+4\right).30.\\ \Leftrightarrow60=90x+120.\\ \Leftrightarrow90x=60-120.\\ \Leftrightarrow90x=-60.\\ \Leftrightarrow x=\dfrac{-2}{3}.\)

\(x\ne1.\)

\(\Leftrightarrow3.16=21\left(x-1\right).\\ \Leftrightarrow48=21x-21.\\ \Leftrightarrow21x=69.\\ \Leftrightarrow x=\dfrac{23}{7}.\)

\(\\ \Rightarrow x=\dfrac{5}{2}y.\) 

\(3x-2y=44.\\ \Rightarrow3.\dfrac{5}{2}y-2y=44.\\ \Leftrightarrow\dfrac{15}{2}y-2y=44.\\ \Leftrightarrow\dfrac{11}{2}y=44.\\ \Leftrightarrow y=8.\)

\(\Rightarrow x=\dfrac{5}{2}y=\dfrac{5}{2}.8=20.\)