#(color(red)(−2t^4)color(blue)(+6t^2)color(green)(+5))−(color(red)(−2t^4)color(blue)(+5t^2)color(green)(+1))#
#color(white)("XXXX")#Possibly easier (and less error prone) if we change the main subtraction to addition:
#=(color(red)(−2t^4)color(blue)(+6t^2)color(green)(+5))+(color(red)(2t^4)color(blue)(-5t^2)color(green)(-1))#
#color(white)("XXXX")#Group by powers of #t#
#= color(red)(-2t^4 + 2t^4)color(blue)(+6t^2-5t^2)color(green)(+5-1)#
#color(white)("XXXX")#Combine terms with equal powers of "t"
#= color(red)(0)color(blue)(+1t^2)color(green)(+4)#