giúp mik làm bài này với

a) $\dfrac{18}{19}$ . x = 36

<-> x = 36 : $\dfrac{18}{19}$ = 38

b) $\dfrac{15}{31}$ . x = 225

<-> x = 225 : $\dfrac{15}{31}$ = 465

c) $\dfrac{11}{19}$ . x = 45

<-> x = 45 : $\dfrac{11}{19}$ = $\dfrac{855}{11}$

d) $\dfrac{6}{7}$ . x = $\dfrac{18}{23}$ 

<-> x = $\dfrac{18}{23}$ : $\dfrac{6}{7}$ = $\dfrac{21}{23}$ 

e) 2$\dfrac{1}{2}$ . x =$\dfrac{5}{6}$ 

2$\dfrac{1}{2}$ = $\dfrac{5}{2}$

<-> $\dfrac{5}{2}$ . x = $\dfrac{5}{6}$ 

<-> x = $\dfrac{5}{6}$ : $\dfrac{5}{2}$ = $\dfrac{1}{3}$ 

g) x : 2$\dfrac{3}{4}$ = 9$\dfrac{5}{8}$ 

2$\dfrac{3}{4}$ = $\dfrac{11}{4}$ ; 9$\dfrac{5}{8}$ = $\dfrac{77}{8}$

<-> x : $\dfrac{11}{4}$ = $\dfrac{77}{8}$ 

<-> x = $\dfrac{77}{8}$ . $\dfrac{11}{4}$ = $\dfrac{847}{32}$ 

h) 7$\dfrac{1}{7}$ . $\dfrac{1}{7}$ . x = 22$\dfrac{1}{8}$ 

7$\dfrac{1}{7}$ = $\dfrac{50}{7}$ ; 22$\dfrac{1}{8}$ = $\dfrac{177}{8}$

<-> $\dfrac{50}{7}$ . $\dfrac{1}{7}$ . x = $\dfrac{177}{8}$ 

<-> $\dfrac{50}{49}$ . x = $\dfrac{177}{8}$ 

<-> x = $\dfrac{177}{8}$ : $\dfrac{50}{49}$ = $\dfrac{8673}{400}$ 

  Xin ctlhn