The answer is 13.
1. Your equation should look like this:
-2°C + 15°c = x
2. To find the answer easily, the simplest way is to change this into a subtraction problem. Take the smallest number of the equation infront of the biggest number, then make them both postitive. After that, add a minus symbol inbetween.
15°C - 2°C = x
3. Subtract the numbers.
15°C - 2°C = 13
