Data:
M = Math books
E = Englisg books
TB = Total books
The total of the books is the addition of the math and english books
[tex]TB\text{ = M+ E}[/tex]
The Math books are: M= E-9 (Nine less that English books (E))
So replacing this in the expression for Total Books:
[tex]TB=(E-9)+E\text{ }\Rightarrow TB=E-9+E[/tex]The final expression is:
[tex]TB=2E-9[/tex]
