Odpowiedź:
[tex]a)\ \ 25\%\ \ to\ \ 3\\\\25\%x=3\\\\\frac{25}{100}x=3\\\\\frac{1}{4}x=3\ \ /\cdot4\\\\x=3\cdot4\\\\x=12\\\\\\b)\ \ 40\%\ \ to\ \ 5\\\\40\%x=5\\\\\frac{40}{100}x=5\\\\\frac{2}{5}x=5\ \ /:\frac{2}{5}\\\\x=5\cdot\frac{5}{2}\\\\x=\frac{25}{2}\\\\x=12\frac{1}{2}\\\\x=12,5[/tex]
[tex]c)\ \ 36\%\ \ to\ \ 9\\\\36\%x=9\\\\\frac{36}{100}x=9\\\\\frac{9}{25}x=9\ \ /:\frac{9}{25} \\\\x=\not9\cdot\frac{25}{\not9}\\\\x=25\\\\\\d)\ \ 80\%\ \ to\ \ 28\\\\80\%x=28\\\\\frac{80}{100}x=28\\\\\frac{4}{5}x=28\ \ /:\frac{4}{5}\\\\x=\not28^7\cdot\frac{5}{\not4_{1}}\\\\x=7\cdot5\\\\x=35[/tex]