I believe it’s b because of the way that it is
A tetrahedron is a shape made out of four triangular faces, and it has a total of <span>six edges
</span>

+ 6 +

= 18
First, simplify

to

/ Your problem should look like:

+ 6 +

= 18
Second, simplify

to

/ Your problem should look like:

+ 6 +

= 18
Third, simplify

+ 6 +

to

+ 6 / Your problem should look like:

+ 6 = 18
Fourth, regroup terms. / Your problem should look like: 6 -

= 18
Fifth, multiply both sides by 7. / Your problem should look like: 42 - x = 126
Sixth, subtract 42 from both sides. / Your problem should look like: -x = 126 - 42
Seventh, simplify 126 - 42 to 84. / Your problem should look like: -x = 84
Eighth, multiply both sides by -1. / Your problem should look like: x = -84
Answer:
x = -84
Rocky ate 42 cups of dog food. Since there are 7 days in a week, 21 cups were eaten per week (3x7). Since the question is asking for the amount in two weeks, you multiply 21x2 to get 42.
4x^2 = 12x
4x^2 - 12x = 0
4x(x - 3) = 0
4x = 0
x = 0...not this one
x - 3 = 0
x = 3 <== ur number