Halp

$\begin{align*} \dfrac{s}{2} + 5t &= 3,\\ 3t - 6s &= 9. \end{align*}$

so ill first multiply the top equation by twelve to get 6s+60t=36

ill rearange the second equation to get -6s+3t=9

ill "add" the two equations to cancel out the s to get 63t=45

t=5/7

ill substitute t back into the first equation to get s/2+25/7=3

multiplying by two gets s+50/7=6

s=6-50/7

s=42/7-50/7

s=-8/7

so the ordered pair $(s,t)$would be $\boxed{(-\frac{8}{7},\frac{5}{7})}$