=[ im sad help me please.?

Question

8)To go to a campsite 12 miles away, you paddle a canoe against the current of a river for 4 hours. During your return trip you paddle with the current, and you travel the same distance in 3 hours. Write and solve a system of equations to find your paddling speed in still water. Find the speed of the current of the river.

A)x + y = 12, x – y = 7; 9.5 mi/h, 0.5 mi/h

B)x + y = 4, x – y = 3; 3.5 mi/h, 0.5 mi/h

C)x + y = 3, x – y = 4; 3.5 mi/h, 0.5 mi/h

D)3x + 4y = 12; 4 mi/h, 3 mi/h

Answer 1

You are looking for 2 items.  The number of (independent) equations needed is equal to the number of items to be found.

The equations need to have Sr (speed of river) and Sc (speed of canoe, if the river was not flowing).

Since you have two trips, you have two equations.

Sc - Sr = 12 mi / 4 hours

Sc + Sr = 12 mi / 3 hours

These are simple to solve as simultaneous equations.

Step 1 add both sides together

Sc +Sc -Sr +Sr = (12mi/4hrs) + (12mi/3hr)

simplify

2Sc = (12mi/4hrs) + (12mi/3hr)

solve for Sc

Then plug Sc into either of the two equations and solve for Sr.

Answer 2

WELL, WHO WOULDN'T BE SAD, TRYING TO SOLVE PUZZLES LIKE THIS.   GIVE YOUR BRAIN A BREAK AND MAYBE YOU WILL CHEER UP!!!

Answer 3

omg! we had a question exactly like this on a test! I can't remember exactly how to do it, buy it do know that it's a D=RT problem (distance=rate*time)i think it might be "B"