Sheila has 5 times as many markers as Dave. Together they have 18 markers. How many markers does Sheila have?

Well seems that ur innocent. deriving equation from here hmm. s=Shelia and d=Dave and s+d=12. but 5d=s so 5d+d=12 and 6d=12 so 2 but this is how much dave has so plug it in to 5d so hmm 2 times 5 is 10 and 10 is the answer