Solution: Page 255 (Unmarked Number Line)

Use Unmarked Number Lines

a. -125 + (-30) = ____

• Start at -125.
• Move further left (negative direction) by 30.
• Result: -155

b. +105 - (-55) = ____

• Subtracting a negative is adding a positive.
• $105 + 55 = 160$.
• Result: +160

c. +80 - (-150) = ____

• $80 + 150 = 230$.
• Result: +230

d. -99 - (-200) = ____

• Start at -99.
• Subtracting -200 means adding 200 (Move Right).
• From -99 to 0 is 99 steps. We have $200 - 99 = 101$ steps left to go right.
• Result: +101