write the following using algebraic notation, using the letter x for any unknown numbers: i think of a number, multiply it by two, then subtract 9

I think of a number.

mmm I chose 8

I multiply it by 2 so that is 2*8

I subtract 9 so that is 2*8-9

Now I do the same thing only I let the number I choose be x. Try it.

(You have to just pretend that x is a number)