G) 8 supra x-3 = 5 supra 7

    8            5
⁻⁻⁻⁻⁻⁻⁻ = ⁻⁻⁻⁻⁻⁻⁻
   x-3          7


Răspuns :

produsul mezilor=produsul extremilor
7×8=5(x-3)
56=5x-15
5x-15=56
5x=56+15
5x=71
x=71/5
verif:
8:(71/5-3)=8:(71-15)/5=8×5/56=5/7
8*7=5*3-x
56=15x
x=56:15
x=3,7