Răspuns: a = 84
Explicație pas cu pas:
[(420 : a ) × 4 + 24] : 4 = 11
(420 : a ) × 4 + 24 = 11 × 4
(420 : a ) × 4 + 24 = 44
(420 : a ) × 4 = 44 - 24
(420 : a ) × 4 = 20
420 : a = 20 : 4
420 : a = 5
a = 420 : 5
a = 84
Verificare
[(420 : 84 ) × 4 + 24] : 4 = 11
= ( 5 × 4 + 24 ) : 4 =
= ( 20+24) : 4 =
= 44 : 4 =
= 11