Identify the elementary row operation used below. Write your answer with one space between every character.

$$\displaystyle\left[\begin{array}{ccccc} -6 &1 &-6 &5 &9 \cr 1 &-5 &4 &-2 &2 \cr -2 &4 &5 &1 &-6 \cr 1 &-5 &0 &6 &7 \cr 7 &-2 &4 &4 &1 \cr \end{array}\right] \rightarrow \displaystyle\left[\begin{array}{ccccc} -6 &1 &-6 &5 &9 \cr 1 &-5 &4 &-2 &2 \cr -14 &28 &35 &7 &-42 \cr 1 &-5 &0 &6 &7 \cr 7 &-2 &4 &4 &1 \cr \end{array}\right]$$ The row operation is .
Note: "E 2 3" indicates equations 2 and 3 are interchanged; "-7 E 1" indicates equation 1 is multiplied by -7; "5 E 2 + E 4" indicates 5 times equation 2 is added to equation 4.