What's the best routine to follow in the gym?

if a girl wants to lose a lot of fat and muscle to be slim? I have both.

i usually do the elliptical machine for 1.5 hours, then I bike for 20 minutes, and then weights for arms. I feel like I'm doing it all wrong cause I'm not seeing results. What's the best routine to follow in the gym?
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thanks so much guys! you all have good points. I do think I'm coasting because I feel no pain after doing the elliptical. I've gotten used to it. I'm gonna try jogging, I suck at running I get asthma. I can't swim either.
What's the best routine to follow in the gym?
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