To find −4 + 1, start at 0. Draw the arrow for −4. Then, from , draw the arrow for 1; the sum is . To find −4 + (−1), start at 0. Draw the arrow for −4. Then, from , draw the arrow for −1; the sum is .

Complete the steps to find the sum of − + by filling in the blanks. Model the equation using straight arrows called
vectors on the number line below.
a. Place the tail of the arrow on .
b. Draw the arrow units to the left of , and stop at − . The direction of the arrow is to the left since you are counting down from .
c. Start the next arrow at the end of the first arrow, or at − .
d. Draw the second arrow units to the right since you are counting up from −.
e. Stopat.
f. Circle the number at which the second arrow ends to in

Rob zombie is better than alice cooper