Word problems and Matrices?

I am having trouble answering these questions for my Algebra 2 class. I'm homeschooled and I don't really have the need resources to figure this out. I'm working on matrices and "honors word problems" and any answers that explain how to solve/write it out will be greatly appreciated!!!

1)A can of white paint costs $16 while a can of green paint costs $20. Susan is mixing 12 cans of paint and will pay $19 per can for the mixture. How many cans of white paint will she purchase?

would this work?

w-white g-green

16w+20g=19 and w+g=12

2)Choose the value of the coefficient determinant (D) in the following system.

8x + 3y = 22

16x + 4y = 26

For this one I got -16. please tell me if it's wrong!

3) Choose the value of the y determinant (Dy) in the following system.

x – 2y = –4

2x – 3y = –3

I'm not sure how to set this one up. :(

4) A gardener is mixing two fertilizers. The first contains 44% of quality soil and the second contains 71% quality soil. To get 18 pounds of the mixed fertilizer with 63.5% of the quality soil, how many pounds of the first brand of soil will she need?

Just set this one up please, don't solve it completely!

5) Choose the value of the x determinant (Dx) in the following system.

6x + y = 1

4x + 3y = –11

I don't know how to set this one up either...

6) Explain, in complete sentences, the process of using Cramer’s Rule to solve the following system of equations. Provide the solution to the system.

2x + 7y = 2

3x + 8y = 2

7) A mom buys three different types of t–shirts for her children, long sleeve, polo, and short sleeve. The long sleeve shirts cost $18 each, the polo’s cost $15 each, and the short sleeve shirts cost $12 each. The mother purchased three less polo’s than she did short sleeves. If the mother purchased 18 shirts at an average of $14 each, find the number of each type of shirt purchased and explain, in complete sentences, how you arrived at this answer.

^This one is driving me nuts. >:/

Thank you so much in advance for the help!!!