Câu 6: B
Câu 7:
$\frac{7}{25}$ = $\frac{7.3}{25.3}$ = $\frac{21}{75}$
$\frac{-4}{15}$ = $\frac{-4.5}{15.5}$ = $\frac{-20}{75}$
b, $\frac{3}{4}$ = $\frac{3.18}{4.18}$ = $\frac{54}{72}$
$\frac{1}{9}$ = $\frac{1.8}{9.8}$ = $\frac{8}{72}$
$\frac{-5}{8}$ = $\frac{-5.9}{8.9}$ = $\frac{-45}{72}$
c, $\frac{54}{-90}$ = $\frac{-54.48}{90.48}$ = $\frac{-2592}{4320}$
$\frac{-180}{288}$ = $\frac{-180.15}{288.15}$ = $\frac{-2700}{4320}$
$\frac{60}{-135}$ = $\frac{-60.32}{135.32}$ = $\frac{-1920}{4320}$
Câu 8:
-4 = 36 : 9 = $\frac{-36}{9}$
$\frac{-2}{3}$ = $\frac{-2.3}{3.3}$ = $\frac{-6}{9}$
0 = 0 : 9 = $\frac{0}{9}$
$\frac{85}{153}$ = $\frac{85 : 17}{153 : 17}$= $\frac{5}{9}$