Question

4a spra 3b =7,8.Calculati valoarea 5a supra 9b.

Answer 1

 

$\displaystyle\bf\\7\!,\!8=\frac{78}{10}\\\\\frac{4a}{3b}=7\!,\!8\\\\\frac{4a}{3b}=\frac{78}{10}\\\\\frac{4}{3}\times\frac{a}{b}=\frac{78}{10}\\\\\frac{a}{b}=\frac{~\dfrac{78}{10}~}{\dfrac{4}{3}}=\frac{78}{10}\times\frac{3}{4}=\frac{78\times3}{10\times4}=\frac{234}{40}=\boxed{\bf\frac{117}{20}}\\\\\\\frac{5a}{9b}=\frac{5}{9}\times\frac{a}{b}=\frac{5}{9}\times\frac{117}{20}= \frac{5\times117}{9\times20}=\boxed{\boxed{\bf\frac{13}{4}}}$