What is the measure of ∠XBC?1. m∠XBC = m∠BAC + m∠BCA2. 3p – 6 = p + 4 + 843. 3p – 6 = p + 884. 2p – 6 = 885. 2p = 94m∠XBC =

we Know that
m∠ABC=180-[(p+4)+84]--------> 180-[p+88]=92-p
m∠ABC=(92-p)°    equation 1
and
m∠ABC+(3p-6)=180----------m∠ABC=180+6-3p
 m∠ABC=186-3p   equation 2
(1)=(2)
(92-p)=186-3p-----------> 186-92=-p+3p--------------> 2p=94

p=47°
therefore
m∠XBC=(3p-6)°---------->(3*47-6)=135°

the answer is 
m∠XBC=135°