Đáp án:
Giải thích các bước giải:
a)
MSC: 216
$\dfrac{3}{8}$=$\dfrac{3.27}{8.27}$ = $\dfrac{81}{216}$
$\dfrac{5}{27}$=$\dfrac{5.8}{27.8}$=$\dfrac{40}{216}$
b)
MSC: 15
$\dfrac{1}{15}$
-6 = $\dfrac{-6.15}{15}$=$\dfrac{-90}{15}$
c)
MSC:120
$\dfrac{11}{120}$
$\dfrac{7}{40}$=$\dfrac{7.3}{40.3}$=$\dfrac{21}{40}$
-90=$\dfrac{-90.120}{120}$=$\dfrac{-10800}{120}$
$\dfrac{5}{20}$=$\dfrac{5.6}{20.6}$=$\dfrac{30}{120}$