Answer:
The ratio of beryllium to aluminum to sillicate is 1:2:6
Step-by-step explanation:
1. First write down the compound:

2. Then to know the ratio between them, write them down separately:
Beryllium: Be
Aluminum: Al
Silicate:

3. Write the quantity of each of them in the compound, that is the subscript:
Beryllium: Be = 1
Aluminum: Al = 2
Silicate:
= 6
4. Therefore the ratio of beryllium to aluminum to sillicate is 1:2:6