Ionization of the first proton from H2SeO4 is complete (H2SeO4 is a strong acid); the acid ionization

Question:

Ionization of the first proton from H2SeO4 is complete (H2SeO4 is a strong acid); the acid ionization constant for the second proton is 1.2 × 10–2.
(a) What would be the approximate hydronium-ion concentration in 0.150 MH2SeO4 if ionization of the second proton were ignored?
(b) The ionization of the second proton must be considered for a more exact answer, however. Calculate the hydronium-ion concentration in 0.150 M H2SeO4, accounting for the ionization of both protons.