Answer:
Explanation:
Let x represent the number of stamps from Europe.
Let y represent the number of stamps from Africa.
Let z represent the number of stamps from Asia.
She has 47 stamps in all. This means that
x + y + z = 47 - - - - - - - - - - - 1
The number of African stamps is 2 times the number of Asian stamps. This means that
y = 2z
She has 20 stamps from Europe. Therefore, substituting x = 20 and y = 2z into equation 1, it becomes
20 + 2z + z = 47
3z = 47 - 20 = 27
z = 27/3 = 9
y = 2z = 2 × 9
y = 18
She has 20 stamps from Europe, 18 stamps from Africa and 9 stamps Asia.