Answer:
Step-by-step explanation:
p = (3n + a)/(n + a)
Cross multiply
p(n + a) = 3n +a
pn + pa = 3n + a
pa - a = 3n - pn
a(p - 1) = n(3 - p)
Dividing by p - 1
a = n(3 - p)/(p - 1)
