hi bro,help you again!
a.Q=k^0.75*L^0.25
constraint function:Q(k,l)=M=120=6k+3L
put it in 入 mumultiplier fucntion:
g(k,l,入）=Q(k,l)+入（m-Q(K,l)
=k^0.75*L^0.25+入*120-6入k-3入l
F.O.C,get three equation equal to "0" respectively:
g^k=0
g^l=0
g^入=0
b.gets results of k,l form the equations above,put them in original fuction,then get optim-output.
c.since Mk=入k,Ml=入l
got,mk-入k=0,ml-入l=0
therefore:入=mk/k=ml/l
get the conclusion verified.