While two forces act on it, a particle is to move at the constant velocity v = (2.69 m/s)ị - (-3.57 m/s)ſ. One of the forces is 2 1 = (2.51 N)î +(-5.45 N).
What is the other force?
Number
i Units

The other force is (-2.51 N)î +(5.45 N)j

Explanation:

The acceleration of the particle is 0 because the velocity is constant, if the accelaration is 0 the net force is 0 (Newton's second law),  so, the second force is minus first force.

de estos colores. sounds about right.