[tex]\it a)\ \ Not\breve am\ pre\c{\it t}ul\ dup\breve a\ prima\ \ reducere\ cu \ b.\\ \\ b-\dfrac{\ \ 20^{(20}}{100}b=408 \Rightarrow b-\dfrac{1}{5}b=408|_{\cdot5} \Rightarrow 5b-b=2040 \Rightarrow 4b=2040|_{:4} \Rightarrow \\ \\ \Rightarrow b=510\ \ell ei\ (pre\c{\it t}ul\ dup\breve a\ prima\ \ reducere)[/tex]
[tex]\it b)\ \ Not\breve am\ \ pre\c{\it t}ul\ ini\c{\it t}ial\ cu\ a.\\ \\ a-\dfrac{\ \ 15^{(5}}{100}a=510 \Rightarrow a-\dfrac{3}{20}a=510|_{\cdot20} \Rightarrow 20a-3a=10200 \Rightarrow \\ \\ \Rightarrow 17a=10200|_{:17} \Rightarrow a=600\ \ell ei\ (pre\c{\it t}ul\ ini\c{\it t}ial)[/tex]
