Three-digit number creation

The number 0,3,7,4 are given. How many three-digit numbers are there:
a) if the numbers can be repeated
b) if the numbers cannot be repeated
c) how many even three-digit numbers if the numbers can be repeated
d) how many odd three-digit numbers if the numbers could be repeated.

Final Answer:

a =  36
b =  36
c =  24
d =  24

Step-by-step explanation:

$a=3\cdot 4\cdot 3=36$

$b=3\cdot 4\cdot 3=36$

$c=3\cdot 4\cdot 2=24$

$d=3\cdot 4\cdot 2=24$

Try another example