1. **Stating the problem:** Simplify the expression $$15 - 15 : 3 + 4$$. 2. **Recall the order of operations:** Division and multiplication are performed before addition and subtraction. 3. **Perform the division first:** $$15 : 3 = 5$$. 4. **Substitute back:** $$15 - 5 + 4$$. 5. **Perform subtraction and addition from left to right:** $$15 - 5 = 10$$, then $$10 + 4 = 14$$. 6. **Final answer:** $$14$$. This matches the given result in the problem. --- Since the user asked to simplify, here is the simplified expression and answer for the first problem only as per instructions.