In the diagram, shown below:
If ∠ABC = 63° and ∠BCA = 54° , then what is ∠DAB?

DAB is 117.

Step-by-step explanation:

You can solve 2 ways, either by adding the opposite angles together or by finding the 3rd angle of the triangle and using linear pair.

First Method: 63 + 54 = 117

Second Method:

180 - 63 - 54 = 63 (All triangles = 180)

180 - 63 = 117 (All linear pairs = 180)

or

step-by-step explanation:

we need to solve for 'x' the following equation:  

we have that:

⇒

⇒ ⇒

factorizing, we get that:

  ⇒

then, the solutions are: or

nothing extraneous has been found!