I’m stuck on a Algebra question and need an explanation.

1. How much of a 67% antifreeze solution must be added to 42 gallons of a 19% solution to obtain a 50% antifreeze solution?

2. 55 gallons of a 28% acid solution are mixed with 40 gallons of a 80% acid solution. What is the acid concentration of the resulting mixture?

Round to the nearest percent.

3. How much of pure (100%) orange juice must be added to 23 gallons of a 27% orange juice solution to obtain a 62% orange juice solution?

4. 28 gallons of a 55% peroxide solution are mixed with how many gallons of pure water (no peroxide) to obtain 18% peroxide solution?

5. A grocer mixes 19 pounds of peanuts selling for 3 dollarspound with 10 pounds of almonds selling for 7 dollarspound. What is the price of the mixture in dollarspound?