Final answer:
To find the number of children in the choir, subtract the number of women and men from the total number of people. There are 30 children in the choir.
Step-by-step explanation:
To find the number of children in the choir, we need to subtract the number of women and men from the total number of people.
Given that half of the choir is women, there are 80/2 = 40 women in the choir.
Since men are 1/4 of the women, there are 40 * (1/4) = 10 men in the choir.
Therefore, the number of children in the choir is 80 - 40 (women) - 10 (men) = 30.
So, the answer is 30 (c).