Tính hợp lí
a (221 + 23 - 58 ) - ( 58 + 221 + 23 )
b ( 132 - 325 ) - ( 214 - 428 ) + ( - 221 )
c ( 97 - 146 ) - (124 - 259 ) + ( -227 )
d ( 472 - 534 ) - ( 126 - 224 ) + (-69 )
e ( 68 - 128 ) - ( 247 - 538 ) + ( - 34 )
g ( 149 - 347 ) - ( 226 - 478 ) + ( -67 )
f ( 121 - 345 ) - (125 - 521 ) + ( - 210 )
a (221+23-58)-(58+221+23)
=221+23-58-58-221-23
=(221-221) + (23-23) +(-58-58)
=-116