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Mila [183]
2 years ago
12

Julie and Eric row their boat (at a constant speed) downstream for 40 miles in 4 hours, helped by the current. Rowing at the sam

e rate the trip back, against the current, takes 10 hours. Find the rate of the current.
Mathematics
1 answer:
Liula [17]2 years ago
4 0

Answer: 3 miles per hour

<u>Step-by-step explanation:</u>

Use the formula "distance (d) = rate (r) x time (t)" to create a system of equations.

Let "r" represent the rate they are rowing

Let "c" represent the current

                            time          rate      distance        <u>EQUATION</u>

Downstream:     4 hours     r + c       40 miles         4(r + c) = 40

Upstream:         10 hours    r - c        40 miles         10(r - c) = 40


Distribute, then eliminate r to solve for c:

Down: 4r + 4c = 40  →   5(4r + 4c = 40)  →   20r + 20c = 200

  Up: 10r - 10c = 40  → -2(10r - 10c = 40) → <u>-20r + 20c</u> =<u>  -80</u>

                                                                                40c = 120

                                                                              <u> ÷40  </u>  <u>÷40 </u>

                                                                                    c =   3

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