[(5,25+6 9/10) : 2,7+(12,8-5,6):4/5]:1,8=
=[(5,25+69/10) : 2,7+7,2 ×5/4]:1,8=
=[(5,25+6,9) : 2,7+9]:1,8=
=(12,15 : 2,7+9):1,8=
=(4,5+9):1,8=
=(4,5+9):1,8=
=13,5:1,8= 7,5
(4,5-3,25)²-(3/2-5/4)²]:(1,8-3/10)=
=[1,25²-(6/4-5/4)²]:(18/10-3/10)=
=(1,25²-1/4²]):15/10=
=(1,25²-1/4²]):3/2=
=(1,5625-0,0625) × 2/3=
=1,5 × 2/3= 1
(1,5+2/5)×5/3-[(0,25+2/3)×0,75-3/20×5/4]:3=
=(15/10+4/10)×5/3-[(25/100+2/3)×75/100-3/20×5/4]:3=
=19/10×5/3-[(1/4+2/3)×3/4-3/16]:3=
=19/6-[11/12×3/4-3/16]:3=
=19/6-[11/16-3/16]:3=
=19/6-8/16:3=
=19/6-1/2:3=
=19/6-1/6=
=18/6=3
