Question

2. tim x biet

a)8/x= 40/45

b)2/5 + x/7=5/6

Answer 1

a) \(\frac{8}{x}=\frac{40}{45}=\frac{8}{9}\)

=> 8 . 9 = x . 8

<=> x = 9 

b) \(\frac{2}{5}+\frac{x}{7}=\frac{5}{6}\)

\(\Leftrightarrow\frac{x}{7}=\frac{5}{6}-\frac{2}{5}=\frac{13}{30}\)

\(\Leftrightarrow x=\frac{13}{30}.7=\frac{91}{30}\)

Answer 2

a)x=45*8/40=9

b)x/7=13/30

x=7*10/30=91/30

Answer 3

a,8/x=40/45

=>8/x=8/9

=>x=9

   Vậy x=9

b,2/5+x/7=5/6

=>x/7=5/6-2/5

=>x/7=13/30

=>x*30=7*13

=>x*30=91

=>x=91/30

=>x=3,0333...

    Vậy x=3,0333...

Answer 4

8/x=40/45 mà 8=40:5

=>8/x=40:5/45:5=8/9

=> x= 9

b,2/5 + x/7 = 5/6

x/7=5/6-2/5

x/7 = 13/30

x x 30 = 7 x 13

x x 30=91

x= 3 dư 1