Răspuns :
Salut,
1 × 2 × 3 × 4 × 7 × 8 × 9 × 10 = 90 × 8 × a × 12
1 × 2 × 3 × 4 × 7 × 8 × 9 × 10 = 720 × a × 12
2 × 3 × 4 × 7 × 8 × 9 × 10 = 720 × a × 12
6 × 4 × 7 × 8 × 9 × 10 = 720 × a × 12
24 × 7 × 8 × 9 × 10 = 720 × a × 12
168 × 8 × 9 × 10 = 720 × a × 12
1 344 × 9 × 10 = 720 × a × 12
12 096 × 10 = 720 × a × 12
120 960 = 720 × a × 12
a = 120 960 ÷ 720 ÷ 12
a = 168 ÷ 12
a = 14
1 × 2 × 3 × 4 × 7 × 8 × 9 × 10 = 90 × 8 × a × 12
2 × 3 × 4 × 7 × 8 × 9 × 10 = 720 × a × 12
6 × 4 × 7 × 8 × 9 × 10 = 720 × a × 12
24 × 7 × 8 × 9 × 10 = 720 × a × 12
168 × 8 × 9 × 10 = 720 × a × 12
1344 × 9 × 10 = 720 × a × 12
12096 × 10 = 720 × a × 12
120960 = 720 × a × 12
720 × a = 120960 : 12
720 × a = 10080
a = 10080 : 720
a = 14