$\text{a)}$  

Obliczamy wartość wyrażenia.

$\frac{37,5\cdot \frac{20}{3}-2\frac{1}{2}:0,045}{\frac{20}{49}\cdot 9,8+0,125:0,75}=\frac{37\frac{5}{10}\cdot \frac{20}{3}-\frac{5}{2}:\frac{45}{1000}}{\frac{20}{49}\cdot 9\frac{8}{10}+\frac{125}{1000}:\frac{75}{100}}=\frac{37\frac{1}{2}\cdot \frac{20}{3}-\frac{5}{2}:\frac{9}{200}}{\frac{20}{49}\cdot \frac{98}{10}+\frac{1}{8}:\frac{3}{4}}=$  

$=\frac{\frac{75}{2}\cdot \frac{20}{3}-\frac{5}{2}\cdot \frac{200}{9}}{\frac{20}{49}\cdot \frac{49}{5}+\frac{1}{8}\cdot \frac{4}{3}}=\frac{\frac{{\cancel{75}}^{25}}{{\cancel{2}}_1}\cdot \frac{{\cancel{20}}^{10}}{{\cancel{3}}_1}-\frac{5}{{\cancel{2}}_1}\cdot \frac{{\cancel{200}}^{100}}{9}}{\frac{{\cancel{20}}^4}{{\cancel{49}}_1}\cdot \frac{{\cancel{49}}^1}{{\cancel{5}}_1}+\frac{1}{{\cancel{8}}_2}\cdot \frac{{\cancel{4}}^1}{3}}=\frac{250-\frac{500}{9}}{4+\frac{1}{6}}=$  

$=\frac{\frac{2250}{9}-\frac{500}{9}}{4\frac{1}{6}}=\frac{\frac{1750}{9}}{\frac{25}{6}}=\frac{{\cancel{1750}}^{70}}{{\cancel{9}}_3}\cdot \frac{{\cancel{6}}^2}{{\cancel{25}}_1}=\frac{140}{3}$  

Obliczamy 1% tej liczby. 

$\frac{\frac{14}{3}}{1,2}=\frac{\frac{140}{3}}{\frac{6}{5}}=\frac{{\cancel{140}}^{70}}{3}\cdot \frac{5}{{\cancel{6}}_2}=\frac{350}{9}$  

Wyznaczamy szukaną liczbę.

$100\cdot \frac{350}{9}=\frac{35000}{9}=3888\frac{8}{9}$  

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$\text{b)}$  

Obliczamy wartość wyrażenia.

$\frac{0,072}{{3,6}^2-7,2\cdot 2,4+{2,4}^2}=\frac{\frac{72}{1000}}{{\left(3\frac{6}{10}\right)}^2-7\frac{2}{10}\cdot 2\frac{4}{10}+{\left(2\frac{4}{10}\right)}^2}=\frac{\frac{9}{125}}{{\left(3\frac{3}{5}\right)}^2-7\frac{1}{5}\cdot 2\frac{2}{5}+{\left(2\frac{2}{5}\right)}^2}=$  

$=\frac{\frac{9}{125}}{{\left(\frac{18}{5}\right)}^2-\frac{36}{5}\cdot \frac{12}{5}+{\left(\frac{12}{5}\right)}^2}=\frac{\frac{9}{125}}{\frac{324}{25}-\frac{36}{5}\cdot \frac{12}{5}+\frac{144}{25}}=\frac{\frac{9}{125}}{\frac{324}{25}-\frac{432}{25}+\frac{144}{25}}=$  

$=\frac{\frac{9}{125}}{-\frac{108}{25}+\frac{144}{25}}=\frac{\frac{9}{125}}{\frac{36}{25}}=\frac{{\cancel{9}}^1}{{\cancel{125}}_5}\cdot \frac{{\cancel{25}}^1}{{\cancel{36}}_4}=\frac{1}{20}$  

Obliczamy 1% tej liczby. 

$\frac{\frac{1}{20}}{40}=\frac{1}{20}\cdot \frac{1}{40}=\frac{1}{800}$  

Wyznaczamy szukaną liczbę.

$100\cdot \frac{1}{800}=\frac{1}{8}=0,125$  

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$\text{c)}$  

Obliczamy wartość wyrażenia.

$\frac{\left(9\frac{3}{4}:5,2+3,4\cdot 2\frac{7}{34}\right):1\frac{9}{16}}{0,31\cdot 8\frac{2}{5}-5,61:27\frac{1}{2}}=\frac{\left(\frac{39}{4}:5\frac{2}{10}+3\frac{4}{10}\cdot \frac{75}{34}\right):\frac{25}{16}}{\frac{31}{100}\cdot \frac{42}{5}-5\frac{61}{100}:\frac{55}{2}}=\frac{\left(\frac{39}{4}:5\frac{1}{5}+3\frac{2}{5}\cdot \frac{75}{34}\right):\frac{25}{16}}{\frac{31}{100}\cdot \frac{42}{5}-\frac{561}{100}:\frac{55}{2}}=$  

$=\frac{\left(\frac{39}{4}:\frac{26}{5}+\frac{{\cancel{17}}^1}{{\cancel{5}}_1}\cdot \frac{{\cancel{75}}^{15}}{{\cancel{34}}_2}\right):\frac{25}{16}}{\frac{31}{{\cancel{100}}_{50}}\cdot \frac{{\cancel{42}}^{21}}{5}-\frac{{\cancel{561}}^{51}}{{\cancel{100}}_{50}}\cdot \frac{{\cancel{2}}^1}{{\cancel{55}}_5}}=\frac{\left(\frac{{\cancel{39}}^3}{4}\cdot \frac{5}{{\cancel{26}}_2}+\frac{15}{2}\right):\frac{25}{16}}{\frac{651}{250}-\frac{51}{250}}=\frac{\left(\frac{15}{8}+\frac{15}{2}\right):\frac{25}{16}}{\frac{600}{250}}=$  

$=\frac{\left(\frac{15}{8}+\frac{60}{8}\right):\frac{25}{16}}{\frac{12}{5}}=\frac{\frac{{\cancel{75}}^3}{{\cancel{8}}_1}\cdot \frac{{\cancel{16}}^2}{{\cancel{25}}_1}}{\frac{12}{5}}=\frac{6}{\frac{12}{5}}={\cancel{6}}^1\cdot \frac{5}{{\cancel{12}}_2}=\frac{5}{2}$  

Obliczamy 1% tej liczby. 

$\frac{\frac{5}{2}}{2,5}=\frac{\frac{5}{2}}{\frac{5}{2}}=\frac{5}{2}\cdot \frac{2}{5}=1$  

Wyznaczamy szukaną liczbę.

$100\cdot 1=100$