Let y varies directly as x. If y=12 when x=4, then write a linear equation. What is value of y when x=5 ?

Let y vary directly as x. if y=12 when x=4, then write a linear equation, what is the value of y when x=5?

x varies directly as the cube of y, x is 32 when y is 4, then what is the value of y when x is 108 ?

If y varies directly as x and y=12, where x=c, what is y in terms of c when x=8 ?

If x varies directly as 3y+1 and x=9 when y=1 , then what values of x when y=5?

x varies directly as (y^2+z^2) . At y = 1 and z = 2, the value of x is 15. Find the value of z, when x = 39 and y = 2 :