Keep the "13" and focus on the "0.67."
Depending upon the degree of accuracy you want, you could convert "0.67" into 67/100, or 0.666666666666666... = 6/9 or 2/3. You'll then end up with 13 67/100 or 13 2/3.
to change decimals to a fraction, we "add as many zeros at the bottom as there are decimals", in this case, there are two decimals, so we'll be using 00,
[tex] \bf 13.\underline{67}\implies \cfrac{1367}{1\underline{00}}\implies 13\frac{67}{100} [/tex]
where do the 13 and 67 come from in the mixed fraction? well, 1367 ÷ 100 gives a quotient of 13, and a remainder of 67, and that's how the mixed fraction is structured.
