On the left, a balanced scale is shown.

Based on that, what can be filled in place of the question mark to balance the scale on the right is equal to _______.

The objects common to both the sides in the first scale are an orange square, a blue triangle, and a green circle.

Removing the common objects from both sides will not affect the balance.

So, after removing the common objects from both sides in the first scale we can see that

1 yellow triangle is balanced by an orange square, a blue triangle, and a green circle.

So, the answer is 1 yellow triangle.