Math helpppp please!!!!!!!

Hi, i just got couple questions in math i need your hellp, how to find the answer:

1)how many different ways can you place the letters A,B,C,D in a row.
2)A husband is one year old older than his wife. Twenty-one years ago he was twice as old as he was, how old are they now ?

Thanks

4 choices for the first letter, 3 for the second, 2 for the third and what's left for the fourth.
Possible arrangements = 4*3*2*1 = 24

h = w+1
h-21 = 2(w-21) {assuming "he was twice as old as he was" is a misprint and should be "he was twice as old as SHE was"}

w+1-21 = 2w-42
-20+42 = w
w =22
h = 23

He is 23. She is 22