Can someone check to see if its right, its only 3 questions

P= $1400,300 r = 7 1/2% t = 4 what is i ? $4.29 $429.00 $4290.00

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?

X-intercept=-5 y-intercept=2 the equation of the line is