Question

Numerele a,b,c sunt direct proportionale 4,5 si 9. a)Determinati cele trei numere stind ca 3 ori a - 2 ori b=c-14 b)Cat la suta din dublul lui b reprezinta numarul a ?

Answer 1

[tex]a)\\\{a, b, c\} d.p. \{4, 5, 9\} =\ \textgreater \ \frac{a}{4} = \frac{b}{5} = \frac{c}{9} = k\\ \frac{a}{4} = k =\ \textgreater \ a=4k\\ \frac{b}{5} = k =\ \textgreater \ b = 5k\\ \frac{c}{9} = k =\ \textgreater \ c=9k\\ 3*a - 2*b = c - 14 =\ \textgreater \ 3 * 4k - 2 * 5k = 9k - 14 =\ \textgreater \ \\ =\ \textgreater \ 12k - 10k = 9k - 15=\ \textgreater \ 2k = 9k - 14=\ \textgreater \ 7k = 14=\ \textgreater \ k = 2\\ a = 4*k = 4 * 2 = 8\\ b=5*k=5*2=10\\ c=9*k=9*2=18 \\b)\\ \frac{p}{100} * 2 * b = a=\ \textgreater \ \frac{p}{100} * 20 = 8 =\ \textgreater \ \frac{p}{5} = 8 =\ \textgreater \ p = 40 =\ \textgreater \ 40 \% [/tex]