Use the 5-step method to solve.

1. Jim has a total of 50 coins. Some are nickels and some are dimes. Altogether he has $4.15. How many dimes and nickels does he have?

2. A sailboat travels 20 miles downstream in 3 hours. It returns in 4 hours. Find the speed of the sailboat in still water and the rate of the current.

3. When the digits of a two-digit number are reversed the new number is 9 more than the original number, and the sum of the digits of the original number is 11. What is the original number?

4. Erin's age is 3 times Waren's. In 4 years she will be twice as old as he will be. how old is each now?

Please help me in figuring out these answers. I'm not so sure in how to solve them. Thanks.