For the following linear systems enter the letter U if the system has a unique solution, the letter N if it has no solution, and the letter I if it has infinitely many solutions.

. $$\begin{array}{rcrcrcl} 3x &+& 4y &+& 5 z &=& 1 \\ 3x &-& 4y &+&5z &=& 1 \\ x &+& y &+& z &=& 1 \\ \end{array}$$
. $$\begin{array}{rcrcrcl} 3x &+& 4y &+& 5 z &=& 1 \\ x &+& 2y &+&3z &=& 1 \\ 4x &+& 6y &+& 8z &=& 2 \\ \end{array}$$
. $$\begin{array}{rcrcrcl} 3x &+& 4y &+& 5 z &=& 1 \\ x &+& 2y &+&3z &=& 1 \\ 4x &+& 6y &+& 8z &=& 4 \\ \end{array}$$