The first thing you need to do is get rid of that 13. Since the 13 is negative, we switch opporations to cancel it out on the side with the fraction. And what you do to one side, you have to do to the other. Add 13 to 35 to get 48.
3/5x = 48
Now all you must do is divide. 48 / 3/5 is 80, and to check 80 x 3/5 is 48.
X= 80
Hope this helped!