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:
$\frac{6}{4+V} + \frac{6}{4-V} =8; \ =\ \textgreater \ \ \frac{V^2-10}{16-V^2}=0; \ =\ \textgreater \ \ V=\sqrt{10} \ \frac{miles}{hour}$

answer: √10

P.S. the roots of the equation are √10 and (-√10), only positive values is needed for V.

7 0

3 years ago

Which<br>expression is equivalent to 1/5m -20

muminat

There are infinite equivalent expressions. Here are some:

1/5(m-100)

20(1/100m-1)

1/5m-(4•5)

If you expand any of these or any of the terms, you will get an equivalent expression.

7 0

3 years ago

I need help, someone please explain. I don't need the answers i just don't get it.

shepuryov [24]

What answers well whats the question?

4 0

3 years ago