Please and Thank you

Jim and Joe started on trips from San Francisco and traveled in opposite directions. Jim traveled 15 km/h faster than Joe. After 4 hours, they were 420 km apart. How fast was each person traveling?

A coin bank contains more than $3 in quarters, dimes, and nickels. The # of dimes is twice the # of quarters and the # of nickels is 3 times the # of quarters. Find the least possible # of quarters in the bank.

Cynthia invested 3 times as much money at 6% as at %5. If the total of simple interest is at least $1150, what is the least possible amount Cynthia has invested at 5%?

Michael drove to a friend's house at a rate of 40 m/h. He came back by the same route, but at a rate of 45 m/h. If the roundtrip took less than 4 hrs, what is the greatest possible distance Michael could have traveled to visit his friend?

Caridad is6 years older than her sister. For years ago she was 4 times as old as her sister. How old is Caridad now?

Jims average score on 3 tests is 82. What is the least he can score on his 4th test so his average will be at least 86?