Need help writing and solving equations.

Please show me how to write out these equations and solve them. I have 10 Algebra equations. Please show all work so I can understand how you arrived at the answer.

1. If C is a 5 x 1 matrix and D is a 3 x 5 matrix, what are the dimensions of DC?
2. Set-up but do not solve a system of equations for the following problem. For $7.52, you purchased 8 pens and highlighters from a local bookstore. Each highlighter cost $1.09 and each pen cost $0.69. How many pens did you buy?
3. A system of equations that has at least one solution is called ________________________.
4. Solve for x in the following system. 5. Solve for x in the following system.

3x + 4y = 8 6x + 6y = -2

y = 3x + 17 y = -x

6. Solve the system using substitution. 7. Solve the system using elimination.

Y = 2x + 4 x +2y = 1

Y = 3x 4x + y = 11

8. When graphing x >1, where does the shading occur? a. above the boundary line

b. right of the boundary line c. below the boundary line d. left of the boundary line

9. Solve for x in the following matrix equation.

10.