Answer:
19.3795 m
Step-by-step explanation:
If sound travels at 343 m/s and it took Karen 0.113 s to hear the echo from the wall, the distance travelled by the sound is:

Note that the distance calculated above is the distance travelled from Karen to the wall and then back from the wall to Karen. Therefore, the distance between Karen and the wall is:

The wall is 19.3795 m away from Karen.
I'm pretty sure that the answer is 13/40
Answer: The required system of equations representing the given situation is

Step-by-step explanation: Given that Sam needs to make a long-distance call from a pay phone.
We are to write a system to represent the situation.
Let x represent the number of minutes Sam talked on the phone and y represents the total amount that he paid for the call.
According to the given information,
with prepaid phone card, Sam will be charged $1.00 to connect and $0.50 per minute.
So, the equation representing this situation is

Also, if Sam places a collect call with the operator he will be charged $3.00 to connect and $0.25 per minute.
So, the equation representing this situation is

Thus, the required system of equations representing the given situation is

The answer would end up being 0.01323