Question

a)y+30%y=-1,3

b)y-25%y=1/2

Answer 1

a)y=1

b)y=2/3

Answer 2

a)

\(y+30\%y=-1,3\\ \Leftrightarrow y+\dfrac{3}{10}y=-\dfrac{13}{10}\\ \Leftrightarrow y\left(1+\dfrac{3}{10}\right)=-\dfrac{13}{10}\\ \Leftrightarrow\dfrac{13}{10}y=-\dfrac{13}{10}\\ \Rightarrow y=-\dfrac{13}{10}:\dfrac{13}{10}\\ \Rightarrow y=-1\)

b)

\(y-25\%y=\dfrac{1}{2}\\ \Leftrightarrow y-\dfrac{1}{4}y=\dfrac{1}{2}\\\Leftrightarrow y\left(1-\dfrac{1}{4}\right)=\dfrac{1}{2} \\ \Leftrightarrow\dfrac{3}{4}y=\dfrac{1}{2}\\ \Rightarrow y=\dfrac{1}{2}:\dfrac{3}{4}\\ \Rightarrow y=\dfrac{1}{2}\cdot\dfrac{4}{3}\\ \Rightarrow y=\dfrac{4}{6}\\ \Rightarrow y=\dfrac{2}{3}\)