Small tug boats pull cruise ships up and down rivers to prevent them from grounding. cruise ships anchor 18km away from the river port. a tug boat can travel 12 km downstream in the same time it takes it to travel 8 km upstream. if the speed of the current is 6 km/h, calculate the time it takes for the tug boats to travel upstream from the cruise ship to the river port. ( show steps) needed asap : )