-
\frac{60-40}{40}*100\%=\frac{20}{40}*100\%=50\%
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2)
(\frac{9}{20}-\frac{1}{12}): \frac{1}{12}*100\%=\frac{27-5}{60}:\frac{1}{12}*100\%=\frac{22}{60}*\frac{12}{1}*100\%=\frac{22}{5}*100\%=440\%
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3)
liczba b jest większa od a
\frac{216-3,888}{3,888}*100\%=\frac{212,112}{3,888}*100\%=54.5555556*100\%\approx 5456\%
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4)
\frac{9,6-7,2}{7,2}*100\%=\frac{2,4}{7,2}*100\%=\frac{1}{3}*100\%=\frac{100}{3}\%=33\frac{1}{3}\%