Ursprünglich
A = a * b
( a + 4 ) * ( b + 4 ) = a * b + 100
ab + 4b + 4a + 16 = ab +100
4a + 4b = 84
( a + 16 ) * ( b + 2 ) = ab + 200
ab + 2a + 16b + 32 = ab + 200
2a + 16b = 168
4a + 4b = 84
2a + 16b = 168 | * 2
4a + 4b = 84
4a + 32b = 336 | abziehen
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- 28b = -252
b = 9
Einsetzen
4a + 4b = 84
4a + 4*9 = 84
4a = 48
a = 12