1. A manufacturer accidentally makes 80 gallons of lemonade that contains only 4% lemon juice. The recipe requires that the lemonade contains 20% lemon juice. Find the amount of pure lemon juice that the manufacturer must add to the mixture to increase the percentage from 4% lemon juice to 20% lemon juice.
2. A poster has a rectangular printed area 140 cm by 180 cm and a blank strip of uniform width around the four edges. The perimetre of the poster is 1 * 1/2 times the perimetre of the printed area. Find the width of the blank strip and the dimensions of the poster.
3. Amy has a total debt of $1,000 between two credit cards. One of them charges 24% annual interest and the other has a promotional interest rate of 12%. If she paid $14 of interest last month, how much money is charged to each credit card?
4. It takes 8 hours for a cheap pump to clear out a flooded basement. It takes only 5 hours for an expensive pump to do so. How long would it take if we owned one of each?
5. A train is going at 1{3 of its usual speed and it takes an extra 30 minutes to reach its destination. Find its usual time to cover the same distance.