let x=papers on Saturday and y=papers on Sunday
First make equations for the information given to you
x+y=52 (total papers) and y= x+8 (he sold 8 more on Sunday)
then since you know y=x+8 then substitute it in the other equation like so
x+(x+8)=52 which means 2x+8=52 which means 2x=44 and therefore x=22
the problem however asks for sunday and not saturday, so solve for y now
y=x+8 which means y=22+8 which means y=30
He sold 30 papers on Sunday
