Question

How to Simplify 6y + 5z + 8y – 3z?

Answer 1

Combine like terms, in which in this case you have the terms of y and z.
Add 6y and 8y, this becomes 14y.Subtract 5z and 3x, this is 2z. You now have 14y + 2z

Answer 2

To simplify, you just condense all of the values with the same variable, based on the signs of those values.
In this example,
6y + 5z + 8y - 3z
is the same as 
6y + 8y + 5z - 3z
which can be simplified to 
14y + 2z
which is the answer to your question.
Hope that helped =)