\(y\times25\%+y\times\frac{3}{4}+y=20\)
\(\Rightarrow y\times\frac{25}{100}+y\times\frac{3}{4}+y=20\)
\(\Rightarrow y\times\frac{1}{4}+y\times\frac{3}{4}+y=20\)
\(\Rightarrow y\times(\frac{1}{4}+\frac{3}{4}+1)=20\)
\(\Rightarrow y\times2=20\)
\(\Rightarrow y=20\div2=10\)
y x 25% +y x 3/4 +y =20
y x25/100 + y x 3/4 + y =20
y x ( 25/100 + 3/4 + 1 ) =20
y x 2 =20
y =20 : 2
y = 10