Jack and walter work in a store's gift-wrapping department. jack can wrap 28 boxes in 2 hours, while walter takes 3 hours to wrap 36 boxes of the same size. one day they work together for t hours to gift wrap 65 boxes. which equation models this situation?

You can calculate the velocity of each individual worker and model the velocity of both working together as the sum of the two individual velocity. Then you solve for the time.

Jack's velocity: 28 boxes / 2 h = 14 boxes / h

Walter's velocity: 36boxes / 3h = 12 boxes / h

Together velocity, V = 14 + 12 = 26 boxes / h

65 boxes => V = 65 boxes/t => t = 65 boxes / V

=65 boxes / 26boxes/h =  2.5 h

The equation that models the situation is V = 65/ t or t = 65/V