multiply your first equation by 3 and get 3x+6z=9
subtract it from 3x+4z=5, in other words (3x+4z=5) - (3x+6z=9)
you get -2z = -4 so z=2, plug that in to x +2(2) = 3 and solve for x, x=-1
multiply 2nd equation by 3, put it together with 3y+4t=9 and subtract
so (3y+4t=9)-(3y+6t=15) and get -2t=-6 or t=3, plug that into y +2(3)=5 and get y=-1
so, x=-1, y=-1, t=3 and z=2