(11-1) 25×599
=25×( A -1)
=25× B -25×1
(11-2) 25×599
(11-3) 25×599
= A ×(39+ B )
=91× C
= D
A 是多少?
B 是多少?
C 是多少?
D 是多少?
=95×( A - B )
=95× C
=8×( A - B )
=8× C
=( A - B )×99
= C ×99- D ×99
= E
E 是多少?
= A ×8+ B ×8
= C + D
=( A + B )×9
= C × D
=( A - B )× C
= D × E
= F
F 是多少?
= A ×( B + C )