Răspuns :
a+b=505
a=4b
4b+b=505
5b=505
b=505:5
b=101
daca b=101 si a=4b=> a=101 x4=> a=404
verificare
a+b=?
404+101=505
x+y=505
x=4y
4y+y=505
5y=505
y=505÷5
y=101
x=4×101
x=404
R: x=404 ; y=101
verificare
404+101=505
x=4y
4y+y=505
5y=505
y=505÷5
y=101
x=4×101
x=404
R: x=404 ; y=101
verificare
404+101=505