Question

use a number line to find each sum. (explore) 1. ( 9 + (-3) = ) ______
number line with marks at 2, 3, 4, 5, 6, 7, 8, 9, 10

1. ( -15 + 4 = ) ______

number line with marks at -18, -16, -14, -12, -10
circle the zero...

Explanation:

Problem 1: \( 9 + (-3) \)

Step1: Start at 9 on the number line.

We begin at the point representing 9 on the given number line (which has marks at 2, 3, 4, ..., 10).

Step2: Move 3 units left (for -3).

Since we are adding -3, we move 3 units to the left from 9. Moving left on a number line decreases the value. So, \( 9 - 3 = 6 \).

Step1: Locate -15 (estimate its position).

The number line has marks at -18, -16, -14, -12, -10. We know that -15 is halfway between -16 and -14 (or we can think of it as 1 unit to the right of -16 and 1 unit to the left of -14).

Step2: Move 4 units right (for +4).

Adding 4 means moving 4 units to the right on the number line. Let's calculate: starting from -15, moving 1 unit right gets us to -14, another to -13, another to -12, and the fourth to -11. So, \( -15 + 4 = -11 \).

Answer:

\( 6 \)

Problem 3: \( -15 + 4 \)