The relationship is not proportional because the boys and girls are in different grades and they are in different activities.
It would be 12 because you have to solve for the percent
The answer is b if you do the equation right
Here the two samples should be comparable .
The total number of cows in the farm = 200
the total number of cows giving milk = 150
the total number of cows in corral = 20
Suppose total number of cows giving milk in corral = x
The ratio of the total number of cows present to the total number of cows giving milk should be same in farm and corral
so : 200 = 20
------- -------
150 x
now we do cross multiplication :
200 x = 150* 20
200x = 3000
x= 3000/200
x= 15
SO we expect 15 cows in corral should be giving milk .
Answer : 15