carjack powersupply
 

i found a powercord for a toshiba laptop and want to use it for my portege 7100, but i cant be shure aobut the power rating, it needs to be 15v, witch it is but the amps required are 3.0 but the supply only says 30 watts, is that comperable? how do i convert watts to amps?

divide the watts by the voltage to get amps.......30 watts should be well enough

While that is the way to measure it, that adapter would only give you 2.0 amps. It should be ok for most circumstances, but if you notice problems during heavy power usage that's probably the cause.