Math question; help problem solving question for 3rd grader; should be easy.?

Question

Carly and Rob combined tier DVD collections. Now they have 42 DVDs in all. Carly had 4 more DVDs than Rob. How many DVDs did Carly have?

I don't know why but I can't figure this easy problem out and I''m a college graduate. I really feel stupid but he has a full page of these to do.

Answer 1

Carly had 23. What I do is half the number ( 42 divided by 2 is 21)

Then since Carly had 4 more, every time you go up once the difference is 2 ( Example  give carly one more dvd and rob would have 1 less. So carly  from the halfed 21 gets 1 which gives her 22. Since Carly got the other dvd from rob he loses it giving him only 20 DVDs. You keep on doing this so you end up with Carly having 23 and Rob 19.)

Answer 2

Carly had 23.

You subtract the four difference from the total number, then divide it by 2 for the lower total. Then, you add the 4 difference back to one of the 19s [the 38 divided by 2] and you get the greater total.

Answer 3

36

Answer 4

i think carly had 25

Answer 5

23