a + b = 325
a : b = 3 rest 5
a = 3b + 5
3b + 5 + b = 4b + 5= 325
4b = 325 - 5
4b = 320
b = 320 : 4
b = 80
a = 3 x 80 + 5
a = 240 + 5
a = 245
a - b = 690
a : b = 2 rest 110
a = 2b + 110
2b + 110 - b = 690
b = 690 - 110
b = 580
a = 2 x 580 + 110
a = 1160 + 110
a = 1270
verificam
1270 - 580 = 690