x=x+12 "x" is the number of science books and "x+12" is the number of science books plus the additional history books.
x=science books so y+12 is the expression
Let x represent the number of science books. The expression for the total number of books is 2 x + 12 , where x + 12 represents the number of history books. Thus, the total number of books combines both science and history books accurately.
;