Anyone good with mathematics? i need , i'll appreciate it.

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

Use the four functions below for this question. compare and contrast these four functions using complete sentences focus on the slope and y- intercept first, and then on any additional properties of each function

Solve the following inequalities and show the solution on a number line. 3/4 (2x-7) ≤ 5