A calculate the H3O concentration in an aqueous solution at

A) calculate the H3O+ concentration in an aqueous solution at 25*C with an OH- concentration of 3.00 x 10^-2M

B) the value of Kw at 100*C is 5.13 x 10^-13. Calculate the H3O+ concentration from the above solution at 100 *C.

Answer in scientific notation. Please show steps

[H+]*[OH-]=10^-14

or 2*10^-2*x=10^-14

or x=5*10^-13 M=[H3O+]

b)2*10^-2*x=5.13*10^-13

or x=2.565*10^-11 M