HELP PLZ! Algebra 10 points?!?

Question

|10 3 -4|
|0 1 -2 | = 12
|X 6 1/5|

this is supposed to be a matrix. can anyone help me find what X would equal? 10 points to the best answer

Answer 1

Determinate of a 3×3 matrix.

Here: a=10, b=3, c=-4, d=0, e=1, f=-2, g=x, h=6 and i=1/5

Add 2x to each side.

2x = 110

Divide each side by 2.

x = 55.