You just have to multiply both by 2, and 3/4 = 6/8. 3 times 2 equals 6, and 4 times 2 equals 8. I hope I helped! :-)
The function
f(x) is even
g(x) is neither even nor odd
h(x) is odd
Steps:
for an even function it holds that f(-x) = f(x):
f(-x) = (-1)^6 x^6 - (-1)^4 x^ 4 = x^6 - x^4 = f(x) => f is even
for an odd h(x) it holds that h(-x) = -h(x):

It is easy to show that g(x) does not match any of the two possibilities above.
The total number of combinations without restrictions is
10 * 10 * 10 * 10 * 10 = 100000
Problem A
10 * 9 * 8 * 7 * 6 = 30240
the number of ways the combination can be set up with no repetition.
The probability of such an event is P = 30240 / 100000 = 0.3024
Problem B
The number of ways that can be done with repetition and no zeros is
9 * 9 * 9 * 9 * 9 = 59049
The probability of such an event is
P = 59049 / 100000 = 0.59049