Dear student,
In this problem we have to use a unknown variable say x,
So Let that unknown number in this problem be x,
Its given that difference between that number and 51.789 leaves 4.789
This can be represented in an equation form as
(x- 51.789 )= 4.789
Now x=4.789+51.789
= 56.578
So value of x=56.578
Hope you understood
Enjoy learning!!
Regards