Question

Daca la suma a doua nr.adunam diferenta lor,obtinem 200,iar daca din suma scadem diferenta, obtinem 170.Care sunt cele doua nr.?

Answer 1

a+b+a-b =200
=> 2a=200
a=100

a+b-(a-b)=170
a+b-a+b=170
2b=170
b=85

Answer 2

$(x+y)+(x-y)=200 \\ (x+y)-(x-y)=170 \\ x+y=170+(x-y) \\ 170+(x-y)+(x-y)=200 \\ 2(x-y)+170=200 \\ 2(x-y)=200-170 \\ 2(x-y)=30 \\ x-y=\frac{30}{2} \\ x-y=15 \\ x+y=170+(x-y)=170+15 \\ x+y=185 \\ x=y+15 \\ y+15+y=185 \\ 2y+15=185 \\ 2y=185-15 \\ 2y=170 \\ y=\frac{170}{2} \\ \boxed{y=85} \\ x=y+15 \\ x=85+15 \\ \boxed{x=100}$