3x + 1 = y(x+2). re arrange to make x the subject of the formulae.

I'm not sure what "to make x the subject of the formula" means.

If it means to solve for y in terms of x:

     3x + 1  =  y( x + 2)     then divide both sides by x + 2:

             y  = (3x + 1) / (x + 2)

If it means to solve for x in terms of y:

     3x + 1  =  y( x + 2)      then multiply out the right side:

     3x + 1  =  xy + 2y        then get all the x-terms on one side and everything else on the other:

     3x - xy  =  2y - 1          then factor out the x-term

     x(3 - y)  =  2y - 1         then divide both sides by 3 - y

     x   =   (2y - 1) /(3 - y)