Let $ t,s,g $ be the weight of one treek, the weight of one squig, and the weight of one goolee, respectively. Then the given information tells us \begin{align*} 10t &=3s+g\\ 2t +g &= s.\end{align*} Since we would like to solve for $ s $ in terms of $ t $, we want to eliminate $ g $. Add the two equations to obtain \begin{align*} 10t+2t+g &= 3s+g+s\\ \Rightarrow 10t+2t &= 3s+s\\ \Rightarrow 4s &= 12t\\ \Rightarrow s &=3t.\end{align*} So one squig weighs $ \boxed{3} $ treeks.