Four women must cross a bridge over a deep ravine in enemy territory in the middle of the night, treacherous bridge will hold on two women at once and it's necessary to carry a lantern while crossing. (Person must stay together while crossing but may return alone) . One of the woman requires five mins for the trip across, one takes ten minu, a third requires 20 and the last takes 25 minutes (each of them can walk slower if necessary but no faster). Unfortunately they only have one lantern among them. How can they make the cro