I am suppose to list variables and give equations. I have six word problems in my homework that I can not seem to figure out I know that of at least 3 that have to use the supply and demand model and another one has to do with mixtures plus motion. I would truly appreciate the help Check them out below:

1. A company budgets $30,000 for advertisement costs promoting a new product. Television ads cost $500 each and radio ads cost $100 each. If the company wants to buy a total of 220 ads, how many of each kind of ads should the company buy?

2. A charity sells tickets for a fundraising dinner. Each adult's ticket costs $10 and each child's ticket costs $5. A total of $1050 was raised by selling 130 tickets. How many of each kind of ticket was sold?

3. A chemist needs 110 milliters of a 31% solution but has only 10% and 43% solutions available. How many milliters of each should be mixed to get the desired solution?

4. The weekly demand model for a new toy is given by D=-5p+80. The weekly supply model for the same toy is 5=3p+40. For these models, p is the price of the toy and N is the number of toys sold or supplied each week to the toy store. Find the price at which supply and demand are equal.

5. A college student earned $8200 during summer vacation working as a waiter in a popular restaurant. The student invested part of the money at 8% and the rest at 7%. If the student received a total of $613 in interest at the end of the year. How much was invested at 8%?

6. A twin-engined aircraft can fly 816 mi. from city A to city B in 3 hrs. with the wind and make the return trip in 8 hrs. against the wind. What is the speed of the wind?

I have been trying all night to figure out these word problems Please help