The answer is: False
This does not mean that AD will be congruent to BC because AD and BC has the same specific angle and volume.
12a + 6 + 3a = 15a + 2
15a = 15a - 4
0 = - 4
Assuming your first equation is y = 5x+9, the equations describe lines that are coincident.
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Multiplying the second equation by -1, it becomes y = 5x+9, the same as the first equation.