Well, this could turn out to be a simple permutation problem: you have ten number choices (0-9) for each digit of a phone number and repetitions are allowed. Technically, there could be as many as \begin{align*}10^{10} = 10,000,000,000\end{align*}, or 10 billion possible phone numbers.
The best and the most correct answer among the choices provided by the question is the first choice. The pair of angles that are vertical is <span>∠KRC and ∠CRH ∠MRC and ∠KRM ∠ERT. </span>I hope my answer has come to your help. God bless and have a nice day ahead!
