A train is scheduled to make a journey of 300km at an average speed of 120km/hr it leaves 6 minutes late and it’s average speed is increased so that it arrives on time find the new average speed

Can someone explain the elimination method to me for this problem?

For one history test, keith had to answer 40 questions. of these 40 questions, keith answered 28 of them correctly. what percent did keith get on his history test? round your answer to the nearest tenth if necessary

Mary works for a company that ships packages and must measure the size of each box that needs to be shipped. mary measures a box and finds the length is 7 inches, the width is 14 inches, and the height is 15 inches. what is the volume of the box? [type your answer as a number.]