Explicație pas cu pas:
a= primul numar
b= al doilea numar
a×3=b×5=k (relatia de proportionalitate)
=> [tex]a=\frac{k}{3}[/tex]
=> [tex]b=\frac{k}{5}[/tex]
40% ×b-20% ×a=12
[tex]\frac{40}{100} *\frac{k}{5} -\frac{20}{100} *\frac{k}{3} =12\\\frac{8k}{100} -\frac{20k}{300} = 12\\\frac{24k}{300} -\frac{20k}{300} =12 / *300\\24k-20k= 3600\\=> k=900[/tex]
=> a=300
=> b=180
