tax rate problem

sir

we are selling Paper products like (Exam Questions paper). we giving paper to printers for printing questions paper and they charged 18%gst for final product. then we sale the question paper to various schools.there is doubt,which tax rate should be charged to schools for selling question papers!. when I check the tax rate in GST site HSN CODE 4911( OTHER PRINTED MATTERS,etc..)



my doubt is purchasing Questions paper is 18% GST rate ,when it's sale to school tax rate is 12%, is it correct or wrong. pls give me a proper answer.