Question

Adrian nu are 100 de timbre,dar ii lipsesc exact atatea cate ar avea peste 100,daca ar avea de 9 ori cate are acum.cate timbre are adrian?

Answer 1

x+y=100, 9x=100+y
y=100-x, 9x=100+(100-x)
9x+x=100+100
10x=200
x=200/10
x=20
Adrian are 20 timbre