Chemistry Acid/Base Question please help!?

5) what is ph of buffer that is 0.36 M lactic acid (CH3CH(OH)COOH) and 0.5 M sodium lactate. Ka for lactic acid = 1.4x10^-4

a. 3.77
b. 4
c. 3.82
d. 0.36
e. 1.4x10^-4


I would appreciate some working out please!!!!
2 answers 2