Question

I really don't understand this lesson can you help me please

Answer 1

Data:

M = Math books

E = Englisg books

TB = Total books

The total of the books is the addition of the math and english books

`TB\text{ = M+ E}`

The Math books are: M= E-9 (Nine less that English books (E))

So replacing this in the expression for Total Books:

`TB=(E-9)+E\text{ }\Rightarrow TB=E-9+E`The final expression is:

`TB=2E-9`