Three objects of equal mass

m₁ = m₂ = m₃ = 1.45 kg

are located on the vertices of an equilateral triangle of length

d = 3.00 m.

A fourth mass

m₄ = 15.5 kg

is at the center of the triangle. What is the net gravitational force on the mass

m₁

that is at the origin? Express your answer in vector form.