My name is Giang

\(\Rightarrow28\left(x-9\right)=20.35\Rightarrow28x-252=700\Rightarrow28x=952\Rightarrow x=34\)

ko con tam trag de tra loi dau

may mà còn nt cho nhau đuoc ko thi chan lam. hazzzz

\(\frac{a}{b}=\frac{a\left(b+2015\right)}{b\left(b+2015\right)}=\frac{ab+2015a}{b\left(b+2015\right)}\)

\(\frac{a+2015}{b+2015}=\frac{b\left(a+2015\right)}{b\left(b+2015\right)}=\frac{ab+2015b}{b\left(b+2015\right)}\)

TH1: a = b

=> ab+2015a = ab+2015b

=> \(\frac{a}{b}=\frac{a+2015}{b+2015}\)

TH2: a > b

=> ab+2015a > ab+2015b

=> \(\frac{a}{b}>\frac{a+2015}{b+2015}\)

TH3: a < b

=> ab+2015a < ab+2015b

rằm là 15

15 con

là d bạn ạ

ko biet