Adding and Subtracting Negative Numbers

Starting at $-5^{\circ }\text{F}$, adding $12^{\circ }\text{F}$ gives $-5+12=7^{\circ }\text{F}$.

First, simplify $-7-(-4)$. Subtracting -4 is the same as adding 4, so $-7+4=-3$. Then, $-3+(-2)=-5$.

First, simplify $-12+(-8)$, which gives -20. Then, subtracting -15 is the same as adding 15, so $-20+15=-5$.

Owing £20 means starting at -20. Paying back £8 is adding 8: $-20+8=-12$, so you still owe £12.

First, simplify $-14+5$, which gives -9. Next, simplify $-10-7$, which gives -17. Subtracting -17 is the same as adding 17, so $-9+17=8$.

Starting at -120, ascending 50 metres gives $-120+50=-70$. Descending 30 metres is subtracting 30, so $-70-30=-100$.