The given measurements may or may not determine a triangle. if not, then state that no triangle is formed. if a triangle is formed, then use the law of sines to solve the triangle, if it is possible, or state that the law of sines cannot be used.

b = 126°, c = 7, b = 12

We are given 2 sides and a NON - included angle.
The Law of sines cannot be used because we need two angles.
The Law of Cosines cannot be used because we need an INCLUDED angle.

When we are given a triangle with side 'b' AND its opposite Angle 'B' and side 'c', there can be no, one or two solutions.
 
In this case, when the side opposite the given angle is greater than the other side (12 is greater than 7) then there is one solution.

Your maths is very weak try yourself this would improve your skills don't depend on others