The first step you will have to do to solve the problem 2x-7=15 is by adding 7 to 15. Think of this, we are working our self backwords in the problem and the last thing that we would do in the problem is minus the seven. So lets continue with the equation. Next we will have to find how much times 2 can go into the sum of 7+15 which would be the answer 11. the answer to the problem is 11. To check if the answer to this problem is correct solve the problem again but this time adding in the number replacement of the variable(in other words the answer you got with the problem you just solved). This is how you would solve equations similar to this one.