Find a context$-$free grammar

$($e$)$ L$=\{$w$\{$a$,$b$\}$ :na$($w$!=$nb$($w$)\}.($f$)$L$=\{$w$\{$a$,$b$\}$ :na$($v$)$nb$($v$),$wherevisanyprefixofw$\}.($g$)$ L$=\{$w$\{$a$,$b$\}$ :na$($w$)=2$nb$($w$)+1\}.($h$)$ L$=\{$w$\{$a$,$b$\}$ :na$($w$)=$nb$($w$)+2\}.$