[tex]10. \\30zl*1.08=32.40zl\\Prawda\\\\42.50*1.08=45.90\\\\Falsz[/tex]
[tex]11. \\d=\frac34c\\d=c-4\\\\c-4=\frac34c /*4\\4c-16=3c\\4c-3c=16\\c=16\\\\d=\frac34*16=3*4=12\\\\\text{Na poczatku roku szkolnego bylo 12 dziewczat i 16 chlopcow}[/tex]
[tex]12. \\x=0.4a\\y=0.6b\\\\P_1=ab\\P_s=xy=0.4a*0.6b=0.24ab = 24\% P_1\\\\Odp. 24\%[/tex]
[tex]13. \\\\a=4cm\\V_1=a^3=64cm^3\\\\b=1.25a=1.25*4cm=5cm\\V_2=b^3=125cm^3\\V_2-V_1=125cm^3-64cm^3=61cm^3\\\\Ocp. C[/tex]
[tex]14. \\s=30km\\t=1.5h\\V_1=\frac{s}t=\frac{30km}{1.5h}=20\frac{km}h\\\\t_2=90min-\frac13*90min=90min-30min=60min=1h\\V_2=\frac{30km}{1h}=30\frac{km}h\\V_2-V_1=30-20=10\\\\Odp. \text{O 10}\frac{km}h[/tex]
15.
[tex]a+b+c=910\\a=\frac34b\\c=\frac3{10}(a+b) = \frac3{10}(\frac34b+\frac44b)=\frac3{10}*\frac74b=\frac{21}{40}b\\\\\frac34b+b+\frac{21}{40}b=910\\\frac{30}{40}b+\frac{40}{40}b+\frac{21}{40}b=910\\\frac{91}{40}b=910 /*40\\91b=36400 /:91\\b=400\\a=\frac34*400=3*100=300\\c=\frac3{10}*(300+400)=\frac3{10}*700=3*70=210\\\\Odp. A, D[/tex]
[tex]16.\\x - \text{cena poczatkowa}\\1.3x - \text{pierwsza zmiana}\\0.6*1.3x=0.78x - \text{druga zmiana}\\(x+0.3x)-0.4*(x+0.3x)=x+0.3x-0.4x-0.12x=0.78x\\\\Prawda\\\\0.78x=400\\Falsz[/tex]
