Phép tính nào đúng là:

\(\frac{8}{{17}} + \frac{5}{{17}} = \frac{{8 + 5}}{{17}} = \frac{{13}}{{17}}\)

\(\frac{8}{{17}} + \frac{5}{{17}} = \frac{{8 + 5}}{{17 + 17}} = \frac{{13}}{{34}}\)

\(\frac{8}{{17}} + \frac{5}{{17}} = \frac{{8 + 17}}{{17 + 5}} = \frac{{25}}{{22}}\)

\(\frac{8}{{17}} + \frac{5}{{17}} = \frac{8}{{17 + 17}} = \frac{8}{{34}}\)