Bantuinn yaaaa….. soal matematika

P = 2q
p x q = c/a
2q x q = 18/1
2q² = 18
q² = 9
q = 3
p = 2q = 2 x 3 = 6
x² + (2a+3) x + 18 = (x-3) (x-6) = x² – 9x + 18
2a + 3 = -9
2a = -12
a = -6

Jadi, nilai a – 1 = -6 – 1 = -7