Isolate #w# by adding #w# to both sides of the equation then subtracting #203#:
# 128-w=203 #
# 128-wcolor(blue)+color(blue)w=203color(blue)+color(blue)w #
# 128color(red)cancelcolor(black)(-wcolor(blue)+color(blue)w)=203color(blue)+color(blue)w #
# 128=203+w #
# 128color(blue)-color(blue)203=203+wcolor(blue)-color(blue)203 #
# 128color(blue)-color(blue)203=203color(blue)-color(blue)203+w #
# 128color(blue)-color(blue)203=color(red)cancelcolor(black)(203color(blue)-color(blue)203)+w #
# 128-203=w #
# -75=w #
# w=-75 #