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.
Answer:
The answer is C. (1.1)
Step-by-step explanation:
Well, a linear function is proportional, a straight line (on a graph). And the numbers must not have the same answer. For instance, if the X input is 5, and the Y output is 7. And then another X input is 5, and the Y output is 8, that's non-linear.
So, the Answer would be the third graph. This is because the X values are steadily increasing, and so are the Y values.
For the X and Y values, for each time X increases by 1, Y increases by -8. This is, linear because both sides are constantly and evenly increasing.
Answer: Rate of A: 5/6
Rate of B: 3/5
A has a higher rate of change
Step-by-step explanation: You calculate slope/rate of change by determining the rise over the run. The rate of change in A is 5/6x, this is bigger than the slope of B.