4x+2z=14,y=x+z+12,-2x-4z=22 using elimination

The line containing the midpoints of the legs of right triangle abc where a(-5,5), b(1, 1), and c(3, 4) are the vertices.

Aubrey read 29 books and eli read 52 books what number is equal to the number of books aubrey read?

What is the value of x in the equation7x+2y=48 when y=3