The grade is the ratio of rise to run, i.e. the slope aka the tangent.
Answer: (a) 6 degrees
For part b, the road is the hypotenuse c of a right triangle whose tangent of the small angle is 1/10. The height h or rise is the side opposite the small angle.
We could just take the sine of the angle we got but let's get it from the tangent exactly.
Dividing by squared cosine
Answer: (b) Rise of 0.199 km