For what value of x will | -2 A ^ T | =20 if A = […] ?

Given that |-2\( { A }^{ T } \)| =20

Also,   \((-2)^{ 2 } \) |\( { A }^{ T } \)|

4|\( { A }^{ T } \)| = 20

Because |\( { A }^{ T }| \) = |A |

So, 20 = 4|A|

20= 4(x-12)

5=x-12

17=x