(25+5)(25-5)=0

Your statement is false

(25+5)(25-5) ≠ 0
it is (30)(20) = 600

What were you trying to do?
To "solve" an equation, it must contain a variable

Your expression shows the "difference of squares"
could be done as 25^ - 5^2
= 625 - 25 = 600