Question

I do not know how to count following formulax + 5 = 3

Answer 1

The x is going to be a negative number to get the 3. so start off minus 5 from plus 5 and minus five from the other side too. the positive 5 and the negative cancel out and then take it fromt here with three and the negative 5. 

Answer 2

Well you would want to find x so you want to be itself
first subtract 5 on both sides to get x by itself and whatever you do to one side you have to do to the other
X +5=3
-5.-5
x= -2 < that's your answer