A customer's lunch costs $7.31 after tax. If the customer wants to leave a 20% tip, what will the total cost be? Please answer

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

Witch represents the inverse of the function f(x)=1/4x-12

Acompany made a profit of 75000 over a period of 6 years on an initial investment of 15000 what is the annual roi