Which expression can be used to approximate the expression below, for all positive numbers a, b, and x, where a does not equal 1, b does not equal 1?

Pls what is the decimal equivalent of 5 over 9? select one: a. 0 point 5 bar over top of 5 b. 0 point 6 bar over top of 6 c. 0 point 8 bar over top of 8 d. 0 point 9 bar over top of 9