I know this is a really stupid question...but I can't figure it out! So, please excuse my ignorance here!

When using dumbbells for an exercise such as a bench press, for example...if I am using a 10 lb. dumbbell in each hand, do I say I'm pressing 10 lbs. (i.e. each arm is pressing 10 lbs.), or do I say I'm pressing 20 lbs. total, both arms combined??

Same question for Hammer Strength equipment. If I have 25 lbs. on each handle, does that mean I'm doing reps with 25 lbs. or 50 lbs.? I feel really dumb asking these questions, but I just don't know the answer!

Finally, on various weight machines, where the plates are only labeled 1, 2, 3, etc. (instead of how many pounds they are), is there a way to know exactly how much one is lifting? I'd really rather be saying 40 lbs. rather than 4 plates, but it seems it differs depending on the machine.

Thanks for any information you can give me!
Rachel