[tex]\quad \huge \quad \quad \boxed{ \tt \:Answer }[/tex]

[tex]\qquad \tt \rightarrow \:4i [/tex]

____________________________________

[tex] \large \tt Solution \: : [/tex]

[tex] \texttt{Lets solve } [/tex]~

[tex]\qquad\displaystyle \tt \rightarrow \: 3x - y[/tex]

[tex] \texttt{[ put x = i, and y = - i ]} [/tex]

[tex]\qquad\displaystyle \tt \rightarrow \: 3(i) - ( - i)[/tex]

[tex]\qquad\displaystyle \tt \rightarrow \: 3i + i[/tex]

[tex]\qquad\displaystyle \tt \rightarrow \: 4i[/tex]

[tex] \texttt{That's our equivalent expression} [/tex] ~