P = \(\frac{1}{4}\)(Qs+10) when P = N10, what is Qs?

P = \(\frac{1}{4}\)Qs = 10
cross multiply

Qs = \(\frac{1}{4} \times \frac{10}{1}\) = 40

When p = 10

Qs = 40 - 10 = 30