Obliczenia:

$20-12\frac{1}{2}=19\frac{2}{2}-12\frac{1}{2}=7\frac{1}{2}$

$20\cdot 12\frac{1}{2}=20\cdot \frac{25}{2}=10\cdot 25=250$

$20:12\frac{1}{2}=20:\frac{25}{2}=20\cdot \frac{2}{25}=4\cdot \frac{2}{5}=\frac{8}{5}=1\frac{3}{5}$

---

$13\frac{1}{3}\cdot 12=\frac{40}{3}\cdot 12=40\cdot 4=160$   

$13\frac{1}{3}:12=\frac{40}{3}\cdot \frac{1}{12}=\frac{10}{3}\cdot \frac{1}{3}=\frac{10}{9}=1\frac{1}{9}$

---

$4\frac{1}{3}:2\frac{1}{2}=4\frac{2}{6}+2\frac{3}{6}=6\frac{5}{6}$

$4\frac{1}{3}-2\frac{1}{2}=4\frac{2}{6}-2\frac{3}{6}=3\frac{8}{6}-2\frac{3}{6}=1\frac{5}{6}$

$4\frac{1}{3}\cdot 2\frac{1}{2}=\frac{13}{3}\cdot \frac{5}{2}=\frac{65}{6}=10\frac{5}{6}$

$4\frac{1}{3}:2\frac{1}{2}=\frac{13}{3}:\frac{5}{2}=\frac{13}{3}\cdot \frac{2}{5}=\frac{26}{15}=1\frac{11}{15}$

---

Uzupełniamy tabelkę:

$a$	$b$	$a+b$	$a-b$	$a\cdot b$	$a:b$
$16$	$2$	$18$	$14$	$32$	$8$
$150$	$30$	$180$	$120$	$4500$	$5$
$20$	$12\frac{1}{2}$	$32\frac{1}{2}$	7 $\frac{1}{2}$	$250$	$1\frac{3}{5}$
$13\frac{1}{3}$	$12$	$25\frac{1}{3}$	$1\frac{1}{3}$	$160$	$1\frac{1}{9}$
$4\frac{1}{3}$	$2\frac{1}{2}$	$6\frac{5}{6}$	$1\frac{5}{6}$	$10\frac{5}{6}$	$1\frac{11}{15}$