How many moles of H3O+ or OH-

Question

must you add per liter of HA solution to adjust its pH from 9.75 to 9.01? Assume a negligible volume change.

……….x 10………Moles of ……………………..h3O+ or

OH-

I got 4.6001 x 10-5 M of h3o+...but it was wrong