Aboat traveled in a river upstream for a distance of 30 miles at a constant rate, r, in miles per hour, and then made the return trip downstream at
a constant rate. if the boat took 4 hours to travel upstream and 3 hours to travel downstream, which system of equations could be used to find
the rate of the river current, c, in miles per hour?
answer
a) 3r - 3c=30
4r + 4c = 30
b)3r + 4c = 30
3r - 4c = 30
c)4r+ 3c = 30
4r - 3c=30
d) 3r+3c = 30
4r – 4c=30

D

Step-by-step explanation:

r = boat's rate

c = current's rate

1. A boat traveled in a river upstream for a distance of 30 miles. Travelling upstream, the current obstructs the movement, so the actual boat's rate is r - c mph.

If the boat took 4 hours to travel upstream, then

2. A boat traveled in a river downstream for a distance of 30 miles. Travelling downstream, the current helps the movement, so the actual boat's rate is r + c mph.

If the boat took 3 hours to travel downstream, then

So, we get the system

4r-4c=30

3r+3c=30

stop cheating

step-by-step explanation: