20.
[tex]100\% - 45\% = 55\% - chlopcy[/tex]
[tex]55\% - 253 \\ 100\% - x \\ \\ x = \frac{100 \times 253}{55} = \frac{25300}{55} = 460os.[/tex]
Odp.B
21.
[tex]1968 - 123\% \\ x - 100\% \\ \\ x = \frac{1968 \times 100}{123} = \frac{196800}{123} = 1600zl[/tex]
Odp.B
22.
[tex]4\% - 420zl \\ 100\% - x \\ \\ x = \frac{100 \times 420}{4} = \frac{42000}{4} = 10500zl[/tex]
Odp.C
23.
[tex]3500 - 100\% \\ 2800 - x \\ \\ x = \frac{2800 \times 100}{3500} = \frac{280000}{3500} = 80\%[/tex]
[tex]100\% - 80\% = 20\%[/tex]
Odp.C
24.
Pole na początku
[tex]20 \times 20 = 400 {cm}^{2} [/tex]
Pole później
[tex]21 \times 21 = 441 {cm}^{2} [/tex]
Czyli
[tex]441 - 100\% \\ 400 - x \\ \\ x = \frac{400 \times 100}{441} = \frac{40000}{441} \approx91\%[/tex]
[tex]100\% - 91\% = 9\%[/tex]
Odp.B
