Answer:
A, B, and C
Explanation:
This question relates to properties of equality, including the addition property of equality. The addition property of equality states that adding the same thing or equivalent values to both sides of an equation maintains equality. We can treat this balance as an equation, with each side of the balance representing the left and right side of an equation.
We are told that the balance is currently equal. This means that 1 square + 1 triangle = 2 circles + 1 triangle. Clearly, the triangles are equal, so 2 circles must be equal to 1 square, as well.
Using this information we can figure out which of the answer choices are adding the same value to both sides.
A) As seen in the paragraph above, 2 circles and 1 square are equal. So, adding 2 circles to the left and 1 square to the right maintains equality.
B) We know that triangles are equivalent, so adding 2 to both sides follows the addition property of equality.
C) Answer C is the same as A but on different sides. The addition property of equality allows you to add equal values to both sides of the equation. Thus, this answer choice is also true.