Explain how ships transport invasive species in the ballast?

Larger ships transport invasive species in their ballast water, while fouling organisms such as barnacles, seaweeds and mussels can move from one location to another by hitching, a ride on a boat, on items you use in the water and even your clothes

answer; both surfaces of the membrane are nonpermeable

if you add everything up correctly you should get 69 i got this because 50 plus 19 is it