According to the Kansas-Nebraska Act, O territories above the 36°30 N line would be free, while those below the line would allow slavery.
O people in each territory would vote on whether to allow slavery.
O Kansas and Nebraska would enter the Union as slave states.
O Kansas and Nebraska would enter the Union as free states.

Part A:

0 = the surface of the swimming pool

Part B:

Since the height of the slide is measured at +10 feet, then this means

that the top of the slide is 10 feet above the surface of the water (0) in the swimming pool.

Part C:

Since 3 feet of the pole was put in the water, then Kayla should mark the of the bottom of the pole as -3 feet.