Answer:
The correct option is D.
Step-by-step explanation:
The given equation is

According to the addition property of equality
and
are equivalent equations.
Use addition property of equality, add 3x on both the sides.


Therefore Sam's work is incorrect because he make calculation mistake.
According to the subtraction property of equality
and
are equivalent equations.
Use subtraction property of equality, subtract 5x from both the sides.


Therefore Roy's work is correct because he used subtraction property.
Option D is correct.
Answer:
I believe the answer is D. I can guarentee you that C is incorrect at least
2 equations, 2 unknowns. Call height H and base B.
From the first sentence:
HB = 216
From the second sentence:
H = ⅔ B
Plug the second into the first and solve for B:
(⅔ B)B = 216
B^2 = 324
B = 18
Plug that back into either of the original 2 equations and solve for H:
H(18) = 216
H = 12
Answer:
0.08072960648
other way around:
5921 divided by 478 is 12.3870292887 (other way around)