how do you solve this problem
If it is written correctly here: 4x - 6x + x - 5x
then you cannot really "solve" it (meaning, find out what x is) because it is not an equation. What you can do though, is combine like terms.
Terms are the items that are being added together. Since all these terms have an x, they are like terms and can be combined. You already know that 4x means "4 times x." When you are working with the terms, you can actually think of the x as being an object; you have 4 x's minus 6 x's plus an x minus 5 x's.
Notice that an x by itself counts as 1 x.
So combine 4-6+1-5 --> -6
4x - 6x + x - 5x = -6x
Hope this helps!