Answer: Yes
Step-by-step explanation: To determine if these side lengths can form a triangle, I attached a rule in the image provided which is very helpful to look at especially when you're new at this.
If a triangle has sides with lengths of 12, 15, and 13, notice that 12 + 15 or 27 is greater than 13.
So the sum of the lengths of two sides of the triangle is greater than the length of the third side.
This means that the triangle with sides of lengths of 12, 15, and 13, is possible.