Răspuns: 25 lei
Explicație pas cu pas:
Notez suma Stefaniei cu ,,s"
[ ( 3 × s - 5 ) × 2 - 4 ] = a → noul rest
a - a/4 - 3 = 99
a - a/4 = 99 + 3
a - a/4 = 102
3 a = 4 × 102 l : 3
a = 136 → noul rest
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[ ( 3 × s - 5 ) × 2 - 4 ] = 136
( 3 × s - 5 ) × 2 = 136 + 4
3 × s - 5 = 140 : 2
3 × s = 70 + 5
s = 75 : 3
s = 25 → suma Stefaniei
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Verific:
( 3 × 25 - 5 ) × 2 - 4 = 136 → noul rest
136 - 136 : 4 - 3 = 136 - 34 - 3 = 99
