What is the electric potential energy of the group of charge

What is the electric potential energy of the group of charges in the figure? Assume that q1 = 2.0 nC , q2 = 2.6 nC , x = 2.5 cm , and y = 4.5 cm?

electric potential energy of two point charge system is given as , U = kq1q2/d

for this system,

U = [ kq1q2 / y ] + [kq1q2 / x] + [k q2 q2 / sqrt(x^2 + y^2) ]

U = kq1q2 [1/0.045 + 1/0.025] + kq^2 / sqrt(0.045^2 + 0.025^2)

U = (9 x 10^9 x 2.6 x 10^-9)[ (62.22 x 2 x 10^-9) + (19.43 x 2.6 x 10^-9) ]

U = 4.094 x 10^-6 J