I am in great doubt if you do understand the meaning of words/(of terms) you use.


The term "solve using matrices", in the language of school students, means to use a calculator, 
to input the numbers into its matrix (or equations) solver and to press the "SOLVE" button.


At this level, the students are not interested, at all, which solution matrix method to use. 
The term "using matrix method" for them means one and only one thing: 

   +----------------------------------------------------------------------+
   | "take a calculator from their backpack and use its matrix solver".   |
   +----------------------------------------------------------------------+


In this connection, which part of the solution is most difficult to you:


    - to write equations ?

    - to get a calculator from your backpack ?

    - to find the solver in your calculator ?

    - to input numbers into the calculator' solver ?

    - to press the "SOLVE" button ?


Which explanation or which help do you expect from tutors ?


Which help do you need ?


In this context, you should write your request in this way:

    - write the system of equations; solve it using the calculator's  matrix solver and present the answer,  

O N L Y .


Do not use any other words.