Physics help pleez?

Question

Speakers A and B are vibrating in phase. They are directly facing each other, are 8.2 m apart, and are each playing a 71.0 Hz tone. The speed of sound is 343 m/s. On the line between the speakers there are three points where constructive interference occurs. What are the distances of these three points from speaker A?

=?m (nearest)
=?m (middle)
=?m (farthest)

I am having a hard time getting the answer. I worked the problem multiple times. For the other answers, I am having the same problem. for my first distance I got the 343/71.0 = 4.83. Then 8.2 - 2x= m 4.83 then I divided that by 2 and got 3.9 - x = m(2.3135)
for the speaker thats farthest away I know you do the length that they are apart, 8.2, minus your nearest distance you got for part A

I just cannot get the correct answer..... grrrrr.....

i guess...that's a easy way to get a "best answer".
Even thou I NEED help.....from someone who can actually help me...
pleez

Answer 1

I think you are missing out on the principle of the problem. The frequency x wavelength = speed of sound. Somehow, you use the wavelength to determine where constructive interference occurs.

Answer 2

You have someone very close to you named Bob or Rob or Robert. He is worried about money. He is afraid to ask for help, but if he doesn't get it he'll be in grave trouble.

Oh, wait... you said you need physics help, not psychic help.

My bad. Sorry!