First, remove the term on the left side of the equation from parenthesis:
#1 + 2n = -2n - 4#
Next, subtract #color(red)(1)# and add #color(blue)(2n)# to each side of the equation to isolate the #n# term while keeping the equation balanced:
#1 + 2n - color(red)(1) + color(blue)(2n) = -2n - 4 - color(red)(1) + color(blue)(2n)#
#1 - color(red)(1) + 2n + color(blue)(2n) = -2n + color(blue)(2n) - 4 - color(red)(1)#
#0 + (2 + color(blue)(2))n = 0 - 5#
#4n = -5#
Now, divide each side of the equation by #color(red)(4)# to solve for #n# while keeping the equation balanced:
#(4n)/color(red)(4) = -5/color(red)(4)#
#(color(red)(cancel(color(black)(4)))n)/cancel(color(red)(4)) = -5/4#
#n = -5/4#