Final answer:
To subtract 8 from 15, draw two number lines and subtract 8 units from 15 on one of the number lines.
Step-by-step explanation:
Step 1. Draw two number lines, one to represent the starting number 15 and another to represent the number being subtracted 8.
Step 2. Mark the starting number 15 on the number line.
Step 3. From the starting number 15, move to the left on the number line by 8 units, marking each step along the way.
Step 4. The final point where the number line ends after moving 8 units to the left from 15 represents the result of subtracting 8 from 15, which is 7.