When we add, we combine two quantities called addends.
When we subtract, we remove one quantity from another quantity.
Expression
?+?
?-?
Let's take a look at the given number line. We will start by considering the bottom arrow.
Notice that the arrow starts at 0 and ends at 3, so the arrow represents 3. This means that the first addend in our addition expression and the first number in our subtraction expression are both 3.
Addition Expression
Subtraction Expression
3+?
3-?
Next, let's look at the top arrow on the number line.
Notice that the arrow ends 4 units to the left of 3. The arrow represents adding - 4. Let's add this information to our table!
Addition Expression
Subtraction Expression
3+( - 4)
3-?
Recall that to subtract an integer, we add its opposite. This means that the top arrow also represents subtracting the opposite of - 4, 4. Finally, we can complete the subtraction expression!
Addition Expression
Subtraction Expression
3+( - 4)
3- 4
Now we can evaluate the expressions! Let's start by performing the addition.
The sum of 3 and - 4 is equal to - 1. Now let's evaluate the subtraction expression.
3- 4= - 1
The difference of 3 and 4 is - 1. Notice that the result of the subtraction expression and the addition expression is the same!
Checking Our Answer
We want to check our solution, just to be sure. To do so, let's consider the given number line.
Looking at the diagram, we can see that the red arrow ends at - 1, which matches the results of our expressions. This means that our solution is correct!
