
Speed and distance
Hey guys I need help figuring out the other half of this problem.
Two kids walks in the same direction along a straight path, at a constant speed. One at 0.90 m/s and the other at 1.9m/s.
The faster kid walks 780m 7.6 minutes faster than the other.
how far would the students have to walk so that the faster student arrives 5.5 min before the slower student?
How would I set up this problem? I've been setting them up as a proportion, but the answers don't make sense.
Thanks for your help.

$\displaystyle D = v_1t_1$
$\displaystyle D = v_2t_2$
$\displaystyle t_2 = t_1 + 5.5$
3 equations 3 unknowns (D, t_1, t_2)