James has $560 and kate had $320 at first. after both of them spent an equal amount of money on dolls, james had 3 times as much money as kate. how much did each of them spent on the doll?

The concept is constant difference

Find the difference between 560 and 320 which is 240 and 240 is the difference after they spent their money so 240 divide by two is Kate's amount in the end take Kate's original amount of money 320 minus the money she had in the end

answer is 200