Question

Daca x+y=12 si x-y=10, atunci x=..... si y=.....

Answer 1

x=11 si y=1
11+1=12
11-1=10

Answer 2

x+y=12
x-y=10
x=10+y
inlocuim cu x=10+y
avem
x+y=12
10+y+y=12
y+y=12-10
2y=2
y=2:2
y=1

inlocuim cu y=1
avem
x+y=12
x+1=12
x=12-1
x=11

deci
x=11
y=1