Question

The product of six and a number is multiplied by nine

Answer 1

I think you want the expression here:
the product of 6 and a number means 6r
multiply by 9 = times 9
So the expression is 6r×9
~JZ
Hope it helps

Answer 2

product of 6 and a number means 6 times something (let's call it x)
6 times x or 6x

product is multipled by 9
(6x) times 9 or 9(6x)
using associative property or commutative I forgot
9(6x)=(9)(6)(x)=(54)(x)=54x