x+a=b/3x

Question

x= ?

i understand that u bring the x to one side but the answer given is 3a/b-3. I do not understand how to get this answer

plz help

to get the answer given, your equation must have been
x+a = (b/3)*x

multiply each term by 3:
3x + 3a = bx
3a = bx - 3x
3a = x(b-3)
then x = 3a/(b-3) as given.