Calculate the percent ionization of 0.110 m lactic acid (ka=1.4×10−4).

You need to have in mind the following equations given two different notations: 
In Organic notation you write the lacti acid calculation like this: 
CH3CH(OH)COOH(aq) <> CH3CH(OH)COOH-(aq) + H+ (aq) 
Now the simplified formula equation will be: 
HC3H5O3(aq) <> H+(aq) + C3H5O3(aq) 
0.110 - x M x M x M 
havign the regular formula you proceed as follows:
Ka = [H+] [C3H5O3] / [HC3H5O3] 
1.4x10^-4 = (x)(x) / (0.110 - x)
Do the maths and you will get the answer.