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2010-03-30T19:48:04+02:00
11 lat temu teraz za 5 lat
matka x-11 x x+5
córka y-11 y y+5

x+5=2(y+5)
x-11=6(y-11)

x+5=2y+10
x-11=6y-66

x-2y=10-5
x-6y=-66+11

x-2y=5/×(-3)
x-6y=-55

-3x+6y=-15
x-6y=-55

-2x=-70/÷(-2)
x=35

x-2y=5
35-2y=5
-2y=5-35
-2y=-30/÷(-2)
y=15

x=35
y=15