a page of a textbook is 7 1/2 wide. the pages are divided into three equal columns with 3/8 in between how wide is each column

I would assume that the first and last columns on the page also have 3/8" from the edge of the page; therefore,

(7 1/2)-(4*3/8) = ??
??/3 = xx.
If I didn't make an error, I obtained 2" for each of the three columns.
Check it.
2*3 = 6" for the three columns.
4(widths) x (3/8") = 1.5"
1.5" + 6" = 7.5"