### Video Transcript

If π sub π΄ is equal to 50π and π sub π΅ is equal to negative 15π, then the relative velocity π sub π΄π΅ is equal to what π.

In this question, weβre given the velocity vectors of π΄ and π΅. And we are asked to find the coefficient of π and the velocity of π΄ relative to π΅. Since both velocity vectors are given in terms of vector π, we know that both bodies are moving along the same one-dimensional axis. However, they are moving in opposite directions. Body π΄ is moving in the positive direction and body π΅ in the negative direction. We recall that the relative velocity of π΄ with respect to π΅ is equal to the velocity of π΄ minus the velocity of π΅. Substituting the values weβre given, this is equal to 50π minus negative 15π, which is the same as adding 15π to 50π.

The relative velocity of body π΄ with respect to π΅ is therefore equal to 65π. And we can therefore conclude that the missing number is 65. It is worth noting that if two bodies are traveling in the opposite direction, the magnitude of their relative velocity will be greater than the individual magnitudes of the velocities. In this case, 65 is greater than both 50 and 15 and is equal to the sum of these values.