We have two sets:

A.... numbers that are divisible by 15

B.... numbers that are divisible by 33

We are looking just numbers between 1 and 10^6.

We need to find:

$\displaystyle

$A \cap B^c$

$

so we need to calculate this

$\displaystyle

[\frac{10^6}{15}(1 - \frac{1}{11})]

$

I understand $\displaystyle \frac{10^6}{15}$, it's logical.

But how do we get;

$\displaystyle

(1 - \frac{1}{11})

$