The Wronskian & Variation of Parameters · Superchallenge problem

Four solutions $y_1,y_2,y_3,y_4$ of the same equation $y''+p(t)y'+q(t)y=0$ have, at $t=0$, the Wronskians $W(y_1,y_2)=2$, $W(y_1,y_3)=3$, $W(y_1,y_4)=4$, $W(y_2,y_4)=5$ and $W(y_3,y_4)=7$. Find $W(y_2,y_3)$ at $t=0$.