how much should i charge for commissions ?

my parents have been talking about having me get a job lately so that i can make income but its pretty hard since i cant drive yet and i spend most of my time doing schoolwork or sleeping—so ive been thinking about opening art commissions !

the only issue is that i have no idea how to price stuff, so i figured that i should get my input from the people first. big, detailed, rendered pieces like the first one take me around 6-7 hours, while simple headshots like the one on the seventh slide only take 45 minutes to an hour, if that means anything to you guys. thanks !! :-)