Răspuns :
{[(3xn)+7]x8-7}:5=29, n=nr initial
(24n+56-7):5=29, inmultim cu 5
24n+56-7=145, 24n=145-49=96, n=96:24=4
[(3 × a + 7) × 8 - 7] : 5 = 29
Metoda mersului invers :
(3 × a + 7) × 8 - 7 = 29 × 5
(3 × a + 7) × 8 - 7 = 145
(3 × a + 7) × 8 = 145 + 7
(3 × a + 7) × 8 = 152
3 × a + 7 = 152 : 8
3 × a + 7 = 19
3 × a = 19 - 7
3 × a = 12
a = 12 : 3
a = 4 (numarul initial)
Metoda mersului invers :
(3 × a + 7) × 8 - 7 = 29 × 5
(3 × a + 7) × 8 - 7 = 145
(3 × a + 7) × 8 = 145 + 7
(3 × a + 7) × 8 = 152
3 × a + 7 = 152 : 8
3 × a + 7 = 19
3 × a = 19 - 7
3 × a = 12
a = 12 : 3
a = 4 (numarul initial)