Melinda can paint 1/4 of a wall in the same time that Desiree can paint 2/5 of a wall. How much of a wall will Melinda have painted when Desiree has finished painting 1 wall?

Atrain leaves little? rock, arkansas, and travels north at 90 kilometers per hour. another train leaves at the same time and travels south at 80 kilometers per hour. how long will it take before they are 680 kilometers? apart?