The common number is 3. 3 times 3 equals 9 3 times 5 equals 15
15
12
How about: 3*5 = 15 as a product of its prime factors
8
It is 5/3 times 9 equals 15
The sum of 45 and 15 equals 60. 15 x 3 equals 45.
3
Divid your number by 4 then times that number by 3 eg. 20 divide 4 equals 5 5 times 3 equals 15
Let the number be x and if 9+2x = 15 then x equals 3
15-3 times 2 equals 15-6 equals 9.
2x + 3 = 15- 3 from both sides2x = 12divide both sides by 2x = 6