Anna
posted by Algebra 2 .
At 9:00 Mary Thorne set out from her house for a picnic, traveling at 15 km/h on her bike. her sister lifet 15 min later and traveled at the speed of 30 km/h. If both her sisters arrived at the picnic area at the same time, how far did each travel?
How would I set this problem up?

didn't they both travel the same distance?
let that distance be x km
so mary's time = x/15
sister's time = x/30
The difference is their times is equal to 1/4 hour.
Translate that into an equation and solve for x