To find out which expressions are equivalent we make the operations in the first expression ans then we see if it is equal to the second one.
A.
in this case we have:
this is not equal to 10r.
B.
In this case we don't have to do any operations, it is clear the expressions are not equal.
C.
This is equal to the second expression, therefore they are equivalent.
D.
In this case:
this is not equivalent to the second expression.
Therefore the answer is C.