Identify the individual terms and then simplify them separately

#color(blue)([(6-3/5)xx(1/4+2/9-5/12) +3/2xx(9/2-7/4-5/2)]xx2/27) color(red)(" "+" "1/4) #

Within the first term, shown in blue, simplify each bracket separately.

#=color(blue)([(5 2/5)xx((9+8-15)/36) +3/2xx((18-7 -10)/4)]xx2/27) color(red)(" "+" "1/4) #

#=color(blue)([color(green)((27/5)xx((2)/36)) color(limegreen)(+3/2xx((1)/4))]xx2/27) color(red)(" "+" "1/4) #

Now cancel where possible

#=color(blue)([color(green)(cancel27^3/5xx1/cancel18^2)color(limegreen)( " "+" "3/2xx1/4)]xx2/27) color(red)(" "+" "1/4) #

Multiply straight across to get:

#=color(blue)([ color(green)(3/10)color(limegreen)(+3/8)]xx2/27) color(red)(" "+" "1/4) #

#=color(blue)([(color(green)(12)color(limegreen)(+15))/40]xx2/27) color(red)(" "+" "1/4) #

#=color(blue)(27/40xx2/27) color(red)(" "+" "1/4) #

#=color(blue)(cancel27/cancel40^20xxcancel2/cancel27) color(red)(" "+" "1/4) #

#=color(blue)(1/20) color(red)(" "+" "1/4) #

Now add the two terms together,

#=(color(blue)(1)color(red)(+5))/20#

#=6/20#

#=3/10#