M is the number of hours of man labour employed
W the number of hours of woman labour employed.
Production is Q, and that requires:
M=(Q/10000)625 ... (1)
W=(Q/10000)400 ... (2)
C(Q)=6M + 5.5W ... (3)
Now the question appears to be:
Does Q = (20)*(M^0.5)*(W^0.5) minimise (3) subject to (1) and (2)?
I'm not sure that this makes any sense!