Đáp án:
Giải thích các bước giải:
$a) 215.98+215.28-430.13$
$=215.98+215.28-215.26$
$=215.(98+28-26)$
$=215.100$
$=21500$
$b) 12.41+3.20.4+2.39.6$
$=12.41+12.20+12.39$
$=12.(41+20+39)$
$=12.100$
$=1200$
$c) 78.31+78.24+17.78+22.78$
$=78.(31+24+17+22)$
$=78.94$
$=7332$
$d) 85.(35-27)-35.(85-27)$
$=85.35-85.27-85.35+35.27$
$=35.27-85.27$
$=27.(35-85)$
$=27.(-50)$
$=(-1350)$