Answer:
3 groups
Step-by-step explanation:
Sopranos = 12
Altos = 9
Find the highest common factor of 12 and 9
12 = 1, 2, 3, 4, 6, 12
9 = 1, 3, 9
The highest common factor of 12 and 9 is 3
Therefore, the choir teacher can only have 3 groups
12 sopranos / 3 groups
= 4 sopranos per group
9 Altos / 3 groups
= 3 altos per group
Each of the 3 groups Will have 4 sopranos and 3 altos each
