This is a good example with what's wrong with Trigonometry. We have a nice ramp with an exact slope, but we're going to turn into an angle we're only going to approximate.
Anyway we have side opposite to theta is 1.5 and hypotenuse is 6 so
[tex]\sin \theta = \dfrac{1.5}{6} = \dfrac 1 4[/tex]
[tex] \theta = \arcsin \frac 1 4 \approx 14.48^\circ [/tex]
Answer: 14
