Simplify each expression if possible by combining like terms. If not possible, write simplified

2x+9x

I don't understand what to do

Didn't mean for it to be proportions as my school subject.

11x

4c-8c

Would it be a negative

Kuai is right.

Here's an excellent explanation of like terms.

http://www.mathsisfun.com/algebra/like-terms.html

Yes. 4c - 8c = -4c

What does it mean if possible by combining like terms?

You couldn't combine like terms if there are no like terms.

Oh, okay. And How would you solve an expression that had exponents too? For example

7d^2 - 5d

Check the website for unlike terms.

To simplify the given expression, we need to combine like terms. Like terms are the terms that have the same variable(s) raised to the same power(s).

In the expression 2x + 9x, both terms have the variable "x" raised to the power 1 and do not have any other variables.

To combine these like terms, we can add their coefficients. The coefficient is the number in front of the variable.

In this case, the coefficient of the term 2x is 2, and the coefficient of the term 9x is 9.

Adding the coefficients gives us 2 + 9 = 11.

Therefore, the simplified expression is 11x.