What’s the area of a circle with a 10 km radius

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

Negative 5 1/12 + negative 4 1/4 + 6 3/4

Given the sequence 7, 14, 28, 56, which expression shown would give the tenth term? a. 7^10 b. 7·2^10 c. 7·2^9