if a tugboat goes upstream 120 miles in 15 hours the return trip takes 10 hours find the speed of the boat and the speed of the current of the return trip? HELP PLEASE!

Question

if a tugboat goes upstream 120 miles in 15 hours the return trip takes 10 hours find the speed of the boat and the speed of the current of the return trip?  HELP PLEASE!

anonymous · Answer

upstream means opposite to flow of river so less total speed and more time
downstream means with the flow of river and so more total speed and less time

eq 120/(x-y)=15 and 120/(x+y)=10
solve

anonymous · Answer

what number gets plugged in for x-y  i dont understand

anonymous · Answer

no number is plugged
2 different eq will be formed..solve the 2 simultaneous equations

anonymous · Answer

so you divide 120by x-y? How

anonymous · Answer

u can move 15 to denominator and x-y to right..similarly to other eq

hero · Answer

Use D = rt and r = (b ± c) to solve

Upstream:
120 = (b - c)15

Downstream:
120 = (b + c)10

hero · Answer

Divide both sides of the first equation by 15; Divide both sides of the second equation by 10 to get:

8 = b - c
12 = b + c

hero · Answer

Now solve the system

anonymous · Answer

my problem is I don't understand how to get the b and c

hero · Answer

Isolate b in both equations, then set b = b

hero · Answer

If I isolate b in both equations I get

b = 8 + c
b = 12 - c

Now setting b = b, I get

8 + c = 12 - c

Can you finish solving for c?

anonymous · Answer

c=4

hero · Answer

8 + c = 12 - c
c + c = 12 - 8
2c = 4
  c = 4/2

anonymous · Answer

so the speed of the boat was 4 and the current is 2

hero · Answer

The current is 2, however, I don't agree with your speed of the boat

anonymous · Answer

omg I never going to understand this
\

hero · Answer

Go to the equation where b was isolated:

b = 8 + c

Substitute c = 2

b = 8 + 2
b = ?

anonymous · Answer

10 how do you understand this stuff I just don't get it

hero · Answer

It's algebra. You just have to be familiar with the basic properties and formulas

anonymous · Answer

I need to you come sit with me at my house and be my teacher. LOL.  thanks for your help

hero · Answer

For this problem, you need to understand the following

1. The relationship between distance, rate, and time (D = rt)
2. Upstream and Downstream
3. The relationship between current speed, boat speed and rate
4. Systems of Equations (Solving multiple equations, variable isolation and substitution)

hero · Answer

Would you say that you are familiar with all of the above?