First of all, the identity property of multiplication (which is what this is I'm assuming) is that the number 1 multiplied by any other number is that number itself. (An example would be 2 multiplied by 1, which would be two) So in this problem, this rule applies too, since 2/3 multiplied by 1 would be 2/3!
Hope this helped :)
If A varies directly with z, and A is 30 and z is 5, then when z is 1, A is 6.
z: 5 ÷ 5 = 1
A: 30 ÷ 5 = 6
Then, when z is 1, A is 6
So, when z is 9, A is...
z: 1 × 9 = 9
A: 6 × 9 = 54
A is 54
