Let's start with basic mental math problems. First, we have 32 plus 15. We can break this down by adding the tens: 30 plus 10 equals 40, then add the ones: 2 plus 5 equals 7, so 40 plus 7 equals 47. Next, 48 minus 23. We subtract 20 first: 48 minus 20 equals 28, then subtract 3: 28 minus 3 equals 25.