pliss saya mohon saya gak bisa matriks

2p + 1 = 9
2p = 8
p = 4

q + 2 = p - q
q + 2 = 4 - q
2q = 2
q = 1

-3r = 2p + q + 3
-3r = 8 + 1 +3
-3r = 12
r = -4

p = 4, q = 1, r = -4