How can you create an equivalent equation by using the properties of equality

1.       Properties of equality refer to two different equations having the same sum of equivalent value.

For example
=> 7 + 3 – 3 = 8 + 2 – 3
=>  10 – 3 = 10 - 3
=> 7 = 7

Property of equality may apply to addition, subtraction, multiplication and division:
For addition:
if x – y = c , then x – y + y = z + y or x = z + y
For subtraction:
if x + y = z , then x + y –y = z – y, or a = z – y
For multiplication
if x/y = z and y is not equal to 0, then x/y * y = z * y, or x = yz
For division
if x * y = z, and y is not equals to 0, then x * y  = z  , or  x = z
                                                                  y         y                y

She should use 12/3 to measure