If angle 1 =145 and angle 2 =40 Prove that angle 3 =105

Question

Another proof that I am trying to figure out how to work the problem out. Any ideas? Link to picture: https://i.imgur.com/7KmmGgP.jpg

Answer 1

Statement                                                    Reasons                        

1. m∠2 = 40º, m∠1 = 145º                 1. Given

2. m∠1 = m∠2 + m∠3                          2. The measure of the exterior angle of a triangle is equal to the sum of                                                                     the measures of the two remote interior angles

3. 145 = 40 + m∠3                              3.  Substitution Property

4. 145 - 40 = m∠3                               4. Subtraction Property

5.  105º = m∠3                                  5. Arithmetic

Answer 2

I saw figure and angle 1 is an exterior angle; therefore angle 1 = sum of remote interior angles 2 & 3.

Therefore angle 3 is 105 degrees.