Răspuns :
( a x 2 - 7 x 8 ) x 2 - 56 = 0
( a x 2 - 56 ) x 2 = 0 + 56
a x 2 - 56 = 56 : 2
a x 2 - 56 = 28
a x 2 = 28 + 56
a x 2 = 84
a = 84 : 2
a = 42 → numarul initial
( a x 2 - 56 ) x 2 = 0 + 56
a x 2 - 56 = 56 : 2
a x 2 - 56 = 28
a x 2 = 28 + 56
a x 2 = 84
a = 84 : 2
a = 42 → numarul initial
( a × 2 - 7 × 8 ) × 2 - 56 = 0 / + 56
( a × 2 - 56 ) × 2 = 56 / : 2
a × 2 - 56 = 28 / + 56
a × 2 = 84
a = 84 : 2
a = 42
( a × 2 - 56 ) × 2 = 56 / : 2
a × 2 - 56 = 28 / + 56
a × 2 = 84
a = 84 : 2
a = 42