B. Because 20 is greter than 18.
1 yd = 3 ft
This means the unit cost per feet is $4.99/3.
Let 'x' represent the length of the material in feet that you can be with $30.
(4.99/3)*x <= 30
Which equation am I looking at
For a better understanding of the solution given here please find the attached file which has the relevant diagram.
To answer this question we will have to make use of <u>the Isosceles Triangle Theorem</u> which states that the perpendicular bisector of the base of an isosceles triangle is also the angle bisector of the vertex angle. Thus, as a corollary we know that is EF is the angle bisector of the vertex angle ∠E, then, EF is the perpendicular bisector of the of the base DK.
Please follow the diagram of a complete understanding of the logic and the solution.
As EF is the angle bisector as given in the question, thus we will have:
.
Also, from the Theorem we know that KF will be half of DK and thus, KF will be:
centimeters.
Likewise, from the same theorem we have: 
30÷10=3
120÷3=40. As a result, there are 40 calories in 10 grams of the crackers. Hope it help!