Tengo una manzana y mi amiga me da 5 mas , cuantas manzanas tengo ahora ?

Samantha swam upstream for some distance in one hour. she then swam downstream the same river for the same distance in only 12 minutes. if the river flows at 4 mph, how fast can samantha swim in still water?

Can somebody me out with this question

Triangle xyz has vertices x(1,3), y(0,0)