First two are close!
First one:
$$\forall x( (Mx \rightarrow Fx)\color{red}{)} \rightarrow ( \forall x(Kx \color{red}{\rightarrow} Fx) \rightarrow \exists x(Kx \land Mx) )$$
... actually, rather than adding a close parenthesis, you can just remove the first open parenthesis:
$$\forall x( Mx \rightarrow Fx) \rightarrow ( \forall x(Kx \rightarrow Fx) \rightarrow \exists x(Kx \land Mx) )$$
Second one:
$$\forall x (Px \color{red}{\rightarrow Wx)} \rightarrow (Pa \leftrightarrow Wa)$$
For the third one:
Notice that this is a conditional statement .. so you need a quantifier for the antecedent, but also a quantifier for the consequent ... try again!