The expression is 
Addition property of equality; if
then 
(Add 25 to each side)
(Apply Additive inverse property:
)
(Additive identity property:
)
(Divide each side by 5)
(Cancel common terms)
(Divide:
)
(Multiply each side by negative one)
(Product of two same signs is positive)
(Take square roots each side)

Product property of square roots:For nonnegative real numbers a and b, 

Rewrite the (
) using imaginary unit; that is
where
.

(Find the square root:
)
(Multiply:
)
The value of
.