Question 14990
Dont get worried its pretty simple.
first analyse the situation
the question is 17-(x3)=5
multiply x3 by '-'
you will have  -3x

now solve

17-3x=5  (shift 17 to the other side)

-3x =5-17
-3x =-12 (take minus common)
 3x =12
  x =12/3
  x =4

Check
17-3x =5
17-3(4)=5
17-12 =5
  5  =5