A, 15,27 - 4,18 - 2,09 = 15,27 - ( 4,18 + 2,09 )
= 15,27 - 6,27
= 9
B,
60-26,75-13,25=60-(26,75+13,25)=60-40=20
C,38,25-18,25+21,64-11,64+9,93=20+10+9,93=39,93
e,(72,69+18,47)-(8,47+22,69)=72,69+18,47-8,47-22,69=72,69-22,69+18,47-8,47=50+10=60
a, 15,27-4,18-2,09
=15,27-(4,18+2,09)
=15,27-6,27
=9