[tex]m_r=m_{rozp}+m_s\\\\m_r_1=500g\\Cp_1=15\%\\\\Cp=\frac{m_s}{m_r_1}*100\%\\15\%=\frac{m_s}{500g}*100\%\\\frac{15}{100}=\frac{m_s}{500g}\\m_s=\frac{15*500g}{100}=15*5g=75g\\\\Cp_2=12\%\\m_r_2=m_r_1+m_{rozp}\\m_r_2=500g+m_{rozp}\\12\%=\frac{75g}{500g+m_{rozp}}*{100\%}\\\frac{12}{100}=\frac{75g}{500g+m_{rozp}}\\12(500g+m_{rozp})=75g*100\\6000g+12m_{rozp}=7500g /-6000g\\12m_{rozp}=1500g\\m_{rozp}=125g[/tex]
Odp. Nalezy dolac 125g wody
