由题意:3s+2t=4 2s-3t=7
(3s+2t)*3=4*3 即9s+6t=12
(2s-3t)*2=7*2 4s-6t=14
所以:9s+6t+4s-6t=12+14 13s=26 s=2
带入原式,得t=-1