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
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