Apharmacist incorporates 6g of coal tar into 120g of a5% coal tar ointment calculate the percetage (w/w) of coal tar in finshed product

Answer 1

look at the amount of tar:

1.0*6 + .05*120 = x(126)
x = 0.095, or 9.5%

Or, consider that 5% of 120g = 6g
So, now you have 12/126 = .095