Lời giải:
a.
$\frac{1}{3}+\frac{8}{15}=\frac{5}{15}+\frac{8}{15}=\frac{13}{15}$
b.
$\frac{9}{2}-\frac{3}{8}=\frac{36}{8}-\frac{3}{8}=\frac{33}{8}$
c.
$\frac{15}{12}\times \frac{36}{40}=\frac{3\times 5}{3\times 4}\times \frac{9\times 4}{10\times 4}$
$=\frac{5}{4}\times \frac{9}{10}=\frac{45}{40}=\frac{45:5}{40:5}=\frac{9}{8}$
d.
$\frac{4}{5}: \frac{6}{15}=\frac{4}{5}: \frac{2}{5}=\frac{4}{5}\times \frac{5}{2}=\frac{4}{2}=2$
a: =5/15+8/15=13/15
b: \(=\dfrac{36}{8}-\dfrac{3}{8}=\dfrac{33}{8}\)
c: \(=\dfrac{5}{4}\cdot\dfrac{9}{10}=\dfrac{45}{40}=\dfrac{9}{8}\)
d: \(=\dfrac{4}{5}\cdot\dfrac{5}{2}=\dfrac{4}{2}=2\)
