Can you please tell me if these are right?

Determine the pH for the following solutions
A [OH-] = 1.0 X 10^-7 M
I got 7
B. [H3O+ = 4.2 X 10 ^-3M
I got 2.4
C. [H3O+]= 0.0001M
I got 4
D. [OH-] = 8.5 X10^-9M
I got 5.9
What are the [H3O+] and [OH-] for a solution with the following pH values?
a. 10.0
For [OH-] I got 1.0*10^-4. and [H3O+] I get 1.0*10^-10
Thank you!

And could you please tell me how to figure this question out?

Solution X has a pH of 9.5 and solution Y has a pH of 7.5.
a. what solution is more acidic?
b. what is the [H3O+] in each?
c. what is the [OH-] in each?

hi al horford