Name the property of equality that justifies the following statement. if p = q, then p - r = q - r a) multiplication property . b) subtraction property . c) symmetric property . d) reflexive property

From the given question : 

If,
p = q
Then,
p - r = q - r

Here,
The commutative property of subtraction has been used.
But,
Subtraction is not commutative over real numbers since we can't say that a – b = b – a for all real numbers a and b.
Hence,
The right answer is : 
B) Subtraction Property .

21/2 or 5/2