I'm not sure how to do this can someone help me

The variable z is directly proportional to x, and inversely proportional to y. when x is 4 and y is 13, z has the value 1.2307692307692. what is the value of z when x= 9, and y= 20

The base of a triangle exceeds the height by 9 inches. if the area is 180 square inches, find the length of the base and the height of the triangle.

The ratio of the measures of the three angles in a triangle is 2: 9: 4. find the measures of the angels