\(75\%\times y+\frac{3}{4}\times y+y=30\)
\(y\times\left(75\%+\frac{3}{4}+1\right)=30\)
\(\frac{5}{2}\times y=30\)
\(y=30:\frac{5}{2}\)
\(y=12\)
\(75\%\times y+\frac{3}{4}\times y+y=30\)
\(y=x\left(\frac{3}{4}+\frac{3}{4}+1\right)=30\)
\(y=x.2,5=30\)
\(y=30:2,5\)
\(y=12\)