APPLY: Solve the following. Provide complete solutions. 1. If y varies directly as x, and x = 13 when y = 26, find x if y= 31. 2. y varies directly as the cube of x. If y = 243 when x = 3, find y if x = 29. 3. The circumference C of a circle varies directly as its radius r. a. What is the constant of variation? b. What is the circumference of a circle whose radius measures / cm? c. Find the radius of the circle whose circumference is 75/2 o