Find the sum of the arithmetic sequence. 3, 5, 7, 9, ..., 21
Choices:
39
120
20
23

23

Step-by-step explanation:

5-3=2

7-5=2

21+2=23

its adding 2 each time the numbers change

exa:

)

3+11

14

step-by-step explanation:

from this example, we can see that subtracting with integers is the same as adding the opposite. we can solve using a number line or by using the saying "keep, change, change" to us solve. it is important to remember that we can subtract a negative and end up with a larger number than we started with.