Explanation:
1) mutiply 12 with 5 and divide it by 2 to get thirty i.e 12*5/2=30
i found this number by the multiples of 12
2) 1/4*5/2=5/8 ounces of yeast to make 30 rolls
3) 1/3*5/2=5/6 cups of powdered milk to make 30 rolls
4) 6*5/2= 30/2=15 tablespoons of butter to make 30 rolls
5) 3 1/2-1/2=3*5/2=15/2=7 1/2 more cups of bread flour than wheet flour to make 30 rolls
6) 3/8= 1/4*3/2
multiplying with 12 will give 18 =3/2*12 =18
it will serve 18 people