a+b+c = 26
a+c+d = 19
b+c+d = 21
b+a+d = 24
adunam cele 4 relatii obtinute si vom afla suma celor 4 numere
3×a+3×b+3×c+3×d = 26+19+21+24
3×(a+b+c+d) = 90
a+b+c+d = 90 : 3 = 30
scadem din suma totala,pe rand, sumele celor 3 numere :
30 - 26 = 4 (d)
30 - 19 = 11 (b)
30 - 21 = 9 (a)
30 - 24 = 6 (c)
verificare:
9+11+6+4 = 30
Raspuns:
a = 9
b = 11
c = 6
d = 4
