The four numbers a, B, C and D are arranged in two rows and two columns, and a vertical line is added on each side, which is recorded as ∣ ABCD ∣ and ∣ ABCD ∣ is defined as ad BC If X - x 17 = 8, please use the properties of the equation to find the value of X

The four numbers a, B, C and D are arranged in two rows and two columns, and a vertical line is added on each side, which is recorded as ∣ ABCD ∣ and ∣ ABCD ∣ is defined as ad BC If X - x 17 = 8, please use the properties of the equation to find the value of X

Compare | X - x 17 ∣ with | ABCD ∣ correspondence
The results are as follows
X corresponds to a
-X corresponds to B
1 corresponds to C
7 corresponds to d
Because ∣ ABCD ∣ = ad BC
So x - x 17 = x * 7 - (- x) * 1 = 7x + x = 8x = 8
So x = 1