Find the probability that a point chosen at random will lie in the shaded area

This is so hard and it’s for a test

Another type of subtraction equation is 16-b=7. explain how you would sole this equation then solve it.

Lizette is training for a marathon. at 7: 00 she left her house and ran until 8: 30, then she walked until 11: 30. she covered a total distance of 18 miles. her running speed was six miles per hour faster than her walking speed. find her running and walking speeds in miles per hour.