A drained triaxial test was conducted on a saturated sand specimen using a stress-path triaxial testing system. The specimen failed when the axial stress reached a value of $100 \mathrm{kN} / \mathrm{m}^{2}$ from an initial confining pressure of $300 \mathrm{kN} / \mathrm{m}^{2}$.
The angle of shearing plane (in degrees) with respect to horizontal is $\_\_\_\_\_\_\_\_$ (rounded off to the nearest integer).