beef feed

The owner of Black Angus Ranch is trying to determine the correct mix of two types of beef feed, A and B which cost 50 cents and 75 cents per pound, respectively.  Five essential ingredients are contained in the feed, shown in the table below.  The table also shows the minimum daily requirements of each ingredient.

The constraint for ingredient 3 is:

A) .5A + .75B = 20

B) .3B = 20

C) .3 B= 20

D) .3B = 20