Solve bx - 4 = 5 for x. Assume that b=0

How do you solve a question like this?

1. writing an equation for an exponential function by 2. a piece of paper that is 0.6 millimeter thick is folded. write an equation for the thickness t of the paper in millimeters as a function of the number n of folds. the equation is t(n)= 3. enter an equation for the function that includes the points. (-2, 2/5) and (-1,2)

If y varies directly as x2 and y=6 when x=6, find the constant of variation.