I need help please !!

What is the size of the matrix resulting from

What is solution for the following system of equations, 2x+8y=4 and x=-3y+5 1) x=14 y=-3 2) x=2 y=-3 3) x=-3 y=-3 4)x=12 y=5

Gabrielle's age is three times mikhail's age. the sum of their ages is 40 . what is mikhail's age? __ years old