Since the triangle is equilateral, we have these equations

    5x = 4y            (1)

and

    5x = x + y + a,    (2)



The last equation is equivalent to

    4x = y + a         (3)


From equation (1), we have  y =  = 1.25x.

Substituting it into equation (3), we get

    4x = 1.25x + a

     2.75x = a

         x =   =  = .


Then from y = 1.25x,  we have  y =  = .


ANSWER.   x = ;  y = .