If ABCD is a parallelogram then what is the measure of < A - <C

Use set builder notation to represent the following set: { -3, -2, -1, 0}

Haruka hiked several kilometers in the morning. she hiked only 66 kilometers in the afternoon, which was 25% less than she had hiked in the morning. how many kilometers did haruka hike in all?

If the value of cos330°is√3/2 then find cos 165°.