11.
a)
[tex]a = 4 \frac{1}{2} = \frac{9}{2} \\ ob = \frac{9}{2} \times \frac{4}{1} = \frac{36}{2} = 18 \\ [/tex]
b)
Ob=64dm
[tex]64 \div 4 = 16[/tex]
12.
a)
[tex]3 \frac{1}{4} + 3 \frac{1}{4} + 6 + 6 = \frac{13}{2 } + 12 = \frac{13}{2} + \frac{24}{2} = \frac{37}{2} = 18 \frac{1}{2} [/tex]
b)
[tex]14 \times 2 + 6 \times 2 = 28 + 12 = 40[/tex]
