Răspuns:
8)
902469
1)abcd
b=4
c=d+3
a+b+c+d=18
Dacă d=1=>c=4
a= 18 - b - c - d =18 - 4 - 4 - 1 = 9 abcd=9441
Dacă d=2=>c=5
a=18 - b - c - d=18 - 4 - 5 - 2= 7 abcd=7452
Daca d=3=>c= 6
a=18 - b - c - d=18 - 4 - 6 - 3= 5 abcd= 5463
Dacă d=4=>c=7
a=18 - 4 - 7 - 4= 3 abcd=3474
Daca d=5=>c=8
a=18 - 4 - 8 - 5= 1 abcd= 1485
2)
a+b=4×(a-b)
a+b+a-b=200=>2a=200=>a=100
100+b=4×(100-b)
100+b=400 - 4b
300=5b=>b=60
3) 28;91
