hmmm okay,

p varies directly as q

Hence, p = kq  (k as a constant) 

q = p/k —— (1)

√q varies inversely as t^2

Hence,  √q = k/t^2

you square the equation

q = k^2/t^4 ——- (2)

in this case let k =1, and sub equation (1) and (2) together, you will get

p=1/t^4

p= k^3/t^4 ???

or 

P= q^3 t^4??

maybe you give the answer, I can explain to you how you get that answer.

hmmm okay,

p varies directly as q

Hence, p = kq  (k as a constant) 

q = p/k —— (1)

√q varies inversely as t^2

Hence,  √q = k/t^2

you square the equation

q = k^2/t^4 ——- (2)

in this case let k =1, and sub equation (1) and (2) together, you will get

p=1/t^4