Lời giải:
$11)$
C1:
$2\frac{1}{3}+3\frac{1}{2}$
$=\frac{2.3+1}{3}+\frac{3.2+1}{2}$
$=\frac{7}{3}+\frac{7}{2}$
$=\frac{7.2+7.3}{6}$
$=\frac{35}{6}$
C2:
$2\frac{1}{3}+3\frac{1}{2}$
$=2+\frac{1}{3}+3+\frac{1}{2}$
$=5+\frac{1}{3}+\frac{1}{2}$
$=5+\frac{5}{6}$
$=\frac{30}{6}+\frac{5}{6}$
$=\frac{35}{6}$
$12)$
C1:
$3\frac{2}{5}+1\frac{1}{3}$
$=\frac{3.5+2}{5}+\frac{1.3+1}{3}$
$=\frac{17}{5}+\frac{4}{3}$
$=\frac{17.3+4.5}{15}$
$=\frac{71}{15}$
C2:
$3\frac{2}{5}+1\frac{1}{3}$
$=3+\frac{2}{5}+1+\frac{1}{3}$
$=4+\frac{2}{5}+\frac{1}{3}$
$=4+\frac{11}{15}$
$=\frac{60}{15}+\frac{11}{15}$
$=\frac{71}{15}$
$13)$
C1:
$5\frac{3}{4}+2\frac{2}{3}$
$=\frac{5.4+3}{4}+\frac{2.3+2}{3}$
$=\frac{23}{4}+\frac{8}{3}$
$=\frac{23.3+8.4}{12}$
$=\frac{101}{12}$
C2:
$5\frac{3}{4}+2\frac{2}{3}$
$=5+\frac{3}{4}+2+\frac{2}{3}$
$=7+\frac{3}{4}+\frac{2}{3}$
$=7+\frac{17}{12}$
$=\frac{84}{12}+\frac{17}{12}$
$=\frac{101}{12}$
