Answer :

to find the value of x we need to use the INVERSE OPERATION of addition which is subtraction. Then we will check our work. lets do it:- 

x + 19 = 13
x = ?
13 - 19 = x 
13 - 19 = -6
x = - 6

CHECK OUR WORK:-
 
x + 19 = 13
x = -6
-6 + 19 = 13 
We were RIGHT!!

So, x = -6

Hope I helped ya!! xD