Consider this option:
1. if to re-write the condition, it is given: total time t=8 hours; upstream=downstream=6 miles; V_boat=4 m/h., V_current=V=?
2. note, that total time=time_upstream+time_downstream, where time_upstream=6miles/(V_boat-V) and time_downstream=6miles/(V_boat+V). Using this it is possible to make up and solve the following equation:

answer: √10
P.S. the roots of the equation are √10 and (-√10), only positive values is needed for V.
Ok nice answer…… well done
Answer:
C) y = 2x + 7; y = 2x + 2
Step-by-step explanation:
The two lines are parallel and so will have the same slope.
From the graph, the slope of both lines are two.
Using slope intercept formula, y=mx+c, with m=2, we have y=2x+c
The blue line has a y-intercept of 2 so the equation is

The red line has a y-intercept of -7 so the equation is

Hence the system is
y=2x+2
y=2x-7
The correct answer is C
Answer:

Step-by-step explanation:

m = slope
b = y-intercept