2x+6x

The expression you've given, 2x + 6x, involves two like terms — terms that have the same variables raised to the same powers. You can combine these like terms by adding their coefficients (the numbers in front of the variables).

For 2x + 6x, you simply add 2 and 6 to get 8, and then keep the same variable x.

So, 2x + 6x simplifies to 8x.