30b^3+8b^2+34b+26/5b+3

What do you want done with that expression?

Is the second-last term (26/5)b or is it 26/(5b) ?

divide

(30b^3+8b^2+34b+26) divided by (5b+3)

carefully study example #7 on this page

http://www.intmath.com/Basic-algebra/3_Division-algebra.php

I still don't understand. Please help!!

It is very impractical to actually type the method of long division in this forum.

There are other pages than the one I suggested that show the step by step procedure.
Try typing "algebraic long division" into the Google window.

Once again

http://www.intmath.com/Basic-algebra/3_Division-algebra.php

did you click on the "answer" part of examples #6 and #7 ?