Answer:
19 
Explanation:
X will refer to the number. 
X+57( the number added to the original.)=4x. (x time 4) 
X+57=4x. 
Subtract x from both sides to get the variable on one side. 
(X+57)-x =(4x)-x
57=3x. You would then divide by 3 on both sides to again get integer isolated. 
57/3=3/3x. 
57/3=19. 3/3=1. 
19=x.