Răspuns :
[(a - 15) × 10 - 100] : 9 = 100
(10a - 150 - 100) : 9 = 100
10a - 250 = 100 × 9
10a - 250 = 900
10a = 900 + 250
10a = 1150
a = 1150/10
a = 115
(10a - 150 - 100) : 9 = 100
10a - 250 = 100 × 9
10a - 250 = 900
10a = 900 + 250
10a = 1150
a = 1150/10
a = 115