Answer :
If the object is moving at a constant speed, acceleration is 0. So:
[tex]F = ma F = m\times 0 F = 0[/tex]
The resultant force is 0. So the force pushing the object must be equal to the friction force acting, so
Friction = 90 N
[tex]F = ma F = m\times 0 F = 0[/tex]
The resultant force is 0. So the force pushing the object must be equal to the friction force acting, so
Friction = 90 N