Answer:
4. Given
6. Definition of verticle angles
7. Algebra/part-whole-postulate/sum of interior angles in a triangle/CPTCTC (Corresponding parts of congruent triangles are congruent)
Explanation:
number 4 is just...given because it shows that they're both right angles
6, it's literally the definition of verticle angles
7, since we know that angle TQU and angle RSU are congruent and angle QUT and SUR are congruent, if we subtract those from 180, that means those two angles also have to be congruent
Also, the two triangles are congruent by LA or ASA, so CPCTC would also work
Part-whole-postulate, same reasoning as algebra.
Sum of interior angles in a triangle, same as algebra.
Hope this helped, let me know if you have any questions.