So first off, you want to get X by itself. To do that you have to do the opposite of what the number is. If the number is negative you add it. If the number is positive, you subtract it. What you do on one side, you do on both.
Answer:your answer would be C because if you are trying to find the amount of baking soda the Trisha used the problem would be 3 times 2 to figure out the answer