Answer:
The answers are
"Using the substitution property:
"x = 15"
Step-by-step explanation:
in the first case, you are substituting the equivalent expresions
of m_P, m_Q and m_R. You are not applying any angle postulate or distributive property.
We know as a fact that the last answer is
"x = 15" because the problem tells us that
12x = 180, so
x = 180/12 = 15
