Question

a tugboat goes 180 miles upstream in 15hrs. the return trip downstream takes 5hrs. Find the speed of the tugboat w/o a current and the speed of the current.

Answer 1

upstream speed is given as

u = b - c

downstream speed is given as

d = b + c

where u = upstream speed
b = speed of boat
c = speed of curent
d = downstream speed

do you follow so far?

Answer 2

i follow. what do I do next ?

Answer 3

now.. can you identify what the upstream speed is?

Answer 4

yes, the upstream speed is 12mph right ?

Answer 5

yes right

Answer 6

how about downstream speed?

Answer 7

the downstream speed is 36mph right ?

Answer 8

right again.

Answer 9

so you have

12 = b - c

an

26 = b + c

are you familiar with systems of linear equations?

Answer 10

sort of

Answer 11

do you know the elimination method?

Answer 12

yes. I think the answer is 24. Is that correct ?

Answer 13

yes! speed of boat = 24

Answer 14

now find speed of current

Answer 15

how ?

Answer 16

rememeber:

d = b + c

you have the value of downstream speed and the speed of the boat

Answer 17

ok, so the speed of the boat is 24 which makes the speed of the current 12 right ?

Answer 18

right

Answer 19

so there's your answer
b = 24 mph
c = 12 mph

Answer 20

ok, thanks

Answer 21

welcome