Question

aflati x din proportia 2x+5 supra 20 = 5 supra 4

Answer 1

$\frac{2x+5}{20} = \frac{5}{4}$ numitorul comun este 20 deci aducem la acelasi numitor amplificand in parteea dreapta cu 5 $\frac{2x+5}{20} = \frac{25}{20} =\ \textgreater \ 2x+5=20 =\ \textgreater \ 2x=25-5 =\ \textgreater \ 2x=20 =\ \textgreater \ x= \frac{20}{2}$ deci x=10 

Answer 2

$\frac{2x+5}{20}$ = $\frac{5}{4}$
4(2x+5)=5x20 (facem inmultire incrucisata )
8x+20=100
8x=100-20
8x=80
x=80:8
x=10