posted by Lily .
the problem is about adding and subtracting polynomials...
This is what I did...
but then, if I add both 5x+4+4x+15
I think this deals with the same problem you posted at 8:49 pm
In this question I think you wanted to subract 5x+4 from 9x+11
that would be 9x+11 - (5x+4)
= 9x + 11 - 5x - 4
= 4x + 7
See how important brackets and the order of operations are ??