From ax and a, if you want x alone, divided ax by a since (ax)/a = x.
Since ax = 5/(6b) and a = 2/(3b), then we divide 5/(6b) by 2/(3b) to find what x equals.
[tex] \dfrac{ax}{a} = \dfrac{\frac{5}{6b}}{\frac{2}{3b}} [/tex]
[tex] x = \dfrac{5}{6b} \times \dfrac{3b}{2} [/tex]
[tex] x = \dfrac{5 \times 3b}{2 \times 6b} [/tex]
[tex] x = \dfrac{15}{12} [/tex]
[tex] x = \dfrac{5}{4} [/tex]
