b, 98,54- (41,82 - 35,72 ) 

=98,54 - 6,1

=92,44

a.8/15+7/4+7/15+5/4

=8/15+7/15+7/4+5/4

=15/15+12/4

=1+3=4

b.98,54-(41,82-35,72)

=98,54-6,1

=92,44

5/8                                                                            1/12

tính thuận tiện:

(8/15+7/15)+(7/4+5/4)=1+3=4

98,54-(41,82+35,72)=98,54-77,54=21

\(\dfrac{15}{8}\) : \(\dfrac{5}{20}\) - \(\dfrac{7}{8}\) : \(\dfrac{1}{4}\) 

= \(\dfrac{15}{8}\) : \(\dfrac{1}{4}\) - \(\dfrac{7}{8}\) : \(\dfrac{1}{4}\)

= ( \(\dfrac{15}{8}\) - \(\dfrac{7}{8}\)) : \(\dfrac{1}{4}\)

= \(\dfrac{8}{8}\) \(\times\) 4

= 4

miu miu cai dau may e

nho k tao khong an dap

BÀI NÀY DỄ ỢT VỚI MK NHƯNG TRÌNH BÀY ĐẦY ĐỦ THÌ MK...CHỊU +_+

a,\(60\times\left(\frac{7}{12}+\frac{4}{15}\right)\)\(=\frac{60\times7}{12}+\frac{60\times4}{15}\)

                                         \(=\frac{12\times5\times7}{12}+\frac{15\times4\times4}{15}\)

                                         \(=5\times7+4\times4\)

                                          \(=35+16\)                                            

                                            \(=51\)

b, \(\frac{1}{2}\times\frac{2}{3}\times\frac{3}{4}\times...\times\frac{8}{9}\)\(=\frac{1\times2\times3\times4\times5\times6\times7\times8}{2\times3\times4\times5\times6\times7\times8\times9}\)

                                                        \(=\frac{1}{9}\)

ai vhat nhìu thì kt bn với mình nha

`a)17/7-3/8+4/7-3/5`

`=(17/7+4/7)-(3/8+3/5)`

`=21/7-(15/40+24/40)=3-39/40=120/40-39/40=81/40`

`b)15/11xx2001/2005-3/11xx2001/2005-1/11xx2001/2005`

`=2001/2005xx(15/11-3/11-1/11)`

`=2001/2005xx11/11`

`=2001/2005`

98,54 − 41,82 − 35,72 = 98,54 − (41,82 + 35,72)

= 98,54 − 77,54 = 21

98,54-41,82-35,72=  98,54 - (41+35,72)

=98,54 - 77,54=21

good luck to you[chúc bạn học tốt]