Răspuns :
a = b + 72
(a + b) : (a - b) = 5 rest 2
a + b = 5(a - b) + 2
a + b = 5a - 5b + 2
b + 72 + b = 5(b + 72) - 5b + 2
2b = - 72 + 360 + 2
2b = 290
b = 290 : 2
b = 145
a = 145 + 72
a = 217
(a + b) : (a - b) = 5 rest 2
a + b = 5(a - b) + 2
a + b = 5a - 5b + 2
b + 72 + b = 5(b + 72) - 5b + 2
2b = - 72 + 360 + 2
2b = 290
b = 290 : 2
b = 145
a = 145 + 72
a = 217
x=y+72
x+y : x-y=5 rest 2
x+y+72=2x
x-y=72
x+y : 72=5 rest 2
x+y=72*5+2
x+y=362
2x=362+72
2x=434
x=434 : 2
x=217
y=217-72
y=145
x+y : x-y=5 rest 2
x+y+72=2x
x-y=72
x+y : 72=5 rest 2
x+y=72*5+2
x+y=362
2x=362+72
2x=434
x=434 : 2
x=217
y=217-72
y=145