Write the chemical equation for the reaction of CH3NH3+ with water. Include physical states and ...

a. Write the chemical equation for the reaction of CH3NH3+ with water. Include physical states and use equilibrium arrow in your answer.
b. Write the acidity constant expression for a.
c. Write the chemical equation for the reaction of HCO3- with water. Include physical states and use equilibrium arrow in your answer.
d. Write the acidity constant expression for c.

I'm assuming you know how to make the equilibrium arrow, because I can't type it. It's like two arrows on top of each other, facing opposite directions. It goes where I put the equals signs.
CH3NH3+(aq) + H2O(l) = CH3NH2(aq) + H3O+(aq)

The acidity constant for CH3NH3+ is Kw/Kb, or with the concentrations [CH3NH2][H3O+] / [CH3NH3+]

HCO3-(aq) + H2O(l) = CO2(g) + OH-(aq) + H2O(l)

The acidity constant for HCO3-, because it's a base, is Kw/Ka, or [CO2][OH-] / [HCO3-]

CH3NH3+ + H2O ------> CH3NH2 + H3O+
Ka = [CH3NH2][H3O+] / [CH3NH3+]
CH3NH3+ + HCO3- ------> CH3NH2 + H2CO3
Ka = [CH3NH2][H2CO3] / [CH3NH3+][HCO3-]