[tex]1) a) \ cp= \frac{md}{ms} *100 \\ cp-\ concentratia \ procentuala \ \\ md- \ masa \ substantei \ dizolvate \ \\ ms- masa \ solutiei \ \\ \\ 350ml=350g \\ 100ml=100g \\ \\ cp=\frac{50}{350} *100= \frac{50}{3,5} \\ \\ \boxed{cp= 14,28} \\ \\ b) ms=md+m H2O \\ ms=50+100 =150g \\ \\cp= \frac{50}{150} *100 = \frac{50}{1,5} \\ \\ \boxed{cp= 33,33}[/tex]
[tex]2)x - \ pretul \ initial \\ 8\% \ din\ x \ = \frac{8}{100} * x= \frac{4}{25} *x = \frac{4x}{25} - \ reducerea\\ \\ x ^{(25} - \frac{4x}{25}= \frac{25x-4x}{25} = \frac{21x}{25} - \ noul \ pret \ \\ \\ 8\% \ din \ \frac{21x}{25} = \frac{8}{100} * \frac{21x}{25}= \frac{4}{25} * \frac{21x}{25}= \frac{ 84x}{625} -\ noua \ reducere\ \\ \\ \frac{21x}{25}^{(25} - \frac{84x}{25} = \frac{ 525x-84x}{25} = \frac{441x}{25} - \ noul \ nou \ pret \\ \\ \frac{441x}{25}= 10580 \\\\ \boxed{x= 599,77} [/tex]
[tex]b) \frac{21x}{25}= \frac{21*599,77}{25} = 503,809 - \ pretul \ dupa \ un \ an \ de \
folosire\ \\ \\ c) 24\% \ din \ 599,77= \frac{24}{100} *599,77= \frac{6}{25} * 599,77= 143,94\ TVA -ul \\ \\ 599,77-143,94= 455,83 -\ pretul \ fara \ TVA [/tex]
[tex]3) 4,25= 4\frac{25}{100}= 4\frac{1}{4}= \frac{17}{4} \\ \\ 2,5= 2\frac{5}{10}= 2\frac{1}{2}= \frac{5}{2} \\ \\ \frac{17}{4} * \frac{2}{5}= \frac{17}{10}[/tex]
