* Note you don't have to read the green portions. They are optional.
Step 1: Put your index finger on 0.
Step 2: The first number in the equation is -1.3 so you know you're counting 1.3 but on the left hand side where all the negative numbers exist. -1.3 is highlighted in orange.
Step 3: Before you tackle the next number remember that you are subtracting -2.4 from -1.3 and whenever -1.3 - (-2.4) happens, it means you are adding. So whenever there are two negatives next to each other, you just make them positive.
-1.3 - (-2.4) becomes -1.3 + 2.4
Why? If I had -1.3 dollars, I owe Jack 1.3 dollars because it is negative. Now let's say out of that debt Jack realizes that he owes me money also and this amout was 2.4 dollars (which is essentially -2.4). He chooses to pay back some of this 2.4 dollars debt by subtracting his debt from my debt that I owe him (-1.3 dollars). The answer that I would receive back would be positive because I know that my 1.3 dollars is smaller than what he owes me so in the end I would be receiving some amount of money to put in my pocket after Jack forgive my debt to him by taking this debt out of his debt to me.
Step 4: Now that we have just one sign to work with for 2.4, we know that because we are adding (+), we go to the right of -1.3 and add 2 first (the whole number) before doing anything with 0.4 value that comes with 2.4
Step 5: Finally, count 0.4 to the right and you have your answer.
Answer is 1.1 from the number line.