The toy's acceleration is to the right because the dog exerts a slightly larger force to the right than your friend's force to the left, according to Newton's second law.
In this scenario, where your friend is playing with a dog and both are exerting forces on a toy, the acceleration of the toy is determined by the net force acting on it according to Newton's second law, which states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.
If your friend is pulling the toy to the left and the dog is pulling with a slightly larger force to the right, the net force on the toy is in the rightward direction (larger force to the right minus smaller force to the left). Therefore, the acceleration of the toy is also in the rightward direction.
The direction of acceleration is always aligned with the direction of the net force acting on the object. In this case, since the dog exerts a larger force to the right than your friend's force to the left, the resulting acceleration is in the direction of the larger force, which is to the right.
It's important to note that acceleration is a vector quantity, meaning it has both magnitude and direction. In this context, the direction of acceleration corresponds to the direction of the net force, and the toy is accelerating to the right.