Operations with integers (Addition and Subtraction)

One way to visualise the additions and subtractions with signed numbers is thinking about going to the grocery store, if you have $30 pesos to buy a chocolate bar that cost $25 pesos, you have enough money because:

30 - 25 = 5

But what if you had $10 pesos to buy a cookie and a soda that cost $15 pesos, would you have enough money to pay for both of them? Integers can answer that for you because:

10 - 15 = -5

You must be thinking WHY DOES IT HAVE TO BE NEGATIVE?!

Another method to learn this is the SADS Method. If the signs are the same, add the numbers and write the same signs. If the signs are different, subtract the numbers and use the sign with the biggest absolute value. 

Subtracting integers involves one extra process: Change the subtraction sign to addition and change the sign of the second number. Now follow the addition rules.

5-(-4) = 5 + (+4)= 9

-3-4= -3+(-4)= -7

7-3= 7+(-3) = 4

If you are still struggling to make sense out of this concepts, go and check this other explaination. 

Ok, now you got it, so let's work!

Solve the following operations: