1. How many liters of water must be added to 9 liters of a 40% solution of hydrochloric acid to make it a 30% solution?
2. How many liters of water must be added to 26 liters of a 15% antifreeze solution to dilute it to a 12% solution?
3. Dr. Green has one solution that is 40% salt and another solution that is 65% salt. How much of the 65% solution must be added to 5 deciliters of the original solution that is 55% salt?
4. Pilar has 7 more nickels than dimes. Their total value is $1.55. How many coins of each type does she have?
5. The cost of a certain metal varies directly as its mass. If 9 kg cost $27, find the cost of 45 kg.
6. Find three consecutive odd integers such that the square of the first is 16 more than the last.
7. The ten digit of a two-digit number is 1 more than 4 times the units digit. The sum of the number and the number with its digits reversed is 121. Find the number.
8. Five out of 12 people use a certain product. How many people use this product in a town of 48,000.
9. The length of a rectangle is 2 m less than 5 times the width. The area is 39 m^2. Find the length and the width.