Give me the correct answer and how to do it step by step number 2 and 3

2. D The sum of 1/2 and 3/4 is the total that Emma walked her dog, so subtracting 1/2 from the total should give you 3/4
3. C When you add 1/2 and 3/4, you get 5/4 or 1 1/4

#3 would be D because you have to take the total amount of hours (h) and subtract either 1/2 or 3/4 because those are the two times and whichever one you pick your answer will be the other one. 
#4 would be C because if you change the denominators to fourths then you will realize it is 3/4 of an hour plus 2/4 of an hour and that equals 5/4 which is also one and one fouth