If Trevor read 30 pages, and then he read "b" more pages, the expression will be
[tex]30+b[/tex]But see that
[tex]30+b=b+30[/tex]It's the same expression, then the correct expressions are
[tex]\begin{gathered} 30+b \\ b+30 \end{gathered}[/tex]It cannot be a division or subtraction, it would be a subtraction if he wants to know how much is left to ready, and the division if he wants to see how many pages he read in "b" days, for example. It would be multiplication if he reads 30 pages "b" days, but it's not the case.
