a+b=0
cd=1
x=5a-5-2a+3b=3(a+b)-5=-5
y=c*cd+d²-d²-c+6=6
1/4(3x+y)-1/5(2x+3y)
=1/4(3*(-5)+6)-1/5(2*(-5)+3*6)
=1/4*(-9)-1/5*8
=-9*5/20-8*4/20
=-77/20
a+b=0
cd=1
x=5a-5-2a+3b=3(a+b)-5=-5
y=c*cd+d²-d²-c+6=6
1/4(3x+y)-1/5(2x+3y)
=1/4(3*(-5)+6)-1/5(2*(-5)+3*6)
=1/4*(-9)-1/5*8
=-9*5/20-8*4/20
=-77/20