What is the value of x? Identify the missing justifications

Answer:
B. Angle Addition Postulate; Subtraction Property of Equality
Step-by-step explanation:
Given:
[tex]m\angle PQR=x+7\\ \\m\angle SQR=x+3\\ \\m\angle PQR+m\angle SQR=m\angle PQS=100^{\circ}[/tex]
Find: x
Solution:
1. [tex]m\angle PQR+m\angle SQR=m\angle PQS[/tex] - Angle Addition Postulate
2. [tex]x+7+x+3=100[/tex] - Substitution Property
3. [tex]2x+10=100[/tex] - Simplify
4. [tex]2x=90[/tex] - Subtraction Property of Equality
5. [tex]x=45[/tex] - Division Property of Equality