i have a 15 and 25 lb dumbbell. i don't know which one to use to gain muscle mass. i can do a max of 40 reps per set for 15 lb and 3 reps per set for a 25 dumbbell. i can't buy a 20 lb. one for now.

I weigh 10 stones and i am 5ft 9inches, how much should i be lifting with my right arm, with 1 dumbbell

For seated miltary press

If i do 185*10 on the last set using a barbell.Today i broke my previous record 185*5-6 to *10 but struggled to do 200 with hammer machine for 6-8 reps

Someone asked me how much i can do on a smith just wondering.
I am 178lbs if anyone is wondering.177 as of today.