A boy walked 10 kilometers. He returned in a car at the rate of 30 kilometers and hour. He was gone for 4 hours. What was his rate while walking?

On a string instrument, the length of a string varies inversely as the frequency of its vibrations. an 11-inch string has a frequency of 400 cylces per second. find the frequency of a 10-icnch string.

You are at a restaurant and owe $38 for your meal. you want to leave a 20% tip. how much will your tip be?

1.based of the diagrams what is the the value of x? 2.how would you verify your answer for x