Committee With Alice or Bob

Use the complement: count committees with neither Alice nor Bob.

Total committees minus committees from the other 8 people.

1. 1. Total committees

   $\left(\genfrac{}{}{0ex}{}{10}{4}\right)=210$.

2. 2. Neither Alice nor Bob

   Choosing all 4 from the remaining 8 people: $\left(\genfrac{}{}{0ex}{}{8}{4}\right)=70$.

3. 3. Complement

   At least one of Alice/Bob: $210-70=140$.

   $$210-70=140$$

Answer: 140