One of the wagers in roulette is to bet that the ball will stop on a number that a multiple of 3. If the ball stops on such a number, the player wins double the amount bet. What is the probability of winning this bet?

Let U $=\{1,2,3,...,2400\}$
Let S be the subset of the numbers in U that are multiples of 3​, and let T be the subset of U that are multiples of 7.
Since ${\displaystyle 2400÷3=800}$​, it follows that $n(S)=n(\{3\cdot 1,3\cdot 2,\cdots ,3\cdot 800\})=800$.
​(a) Find​ n(T) using a method similar to the one that showed that ${\displaystyle n\left(S\right)=800}$.
(b) Find ${\displaystyle n(S\cap T)}$.
(c) Label the number of elements in each region of a​ two-loop Venn diagram with the universe U and subsets S and T.
Questions:Find n(T) ? Find n(SnT)

The simplest form of the expression, $\sqrt[3]{40x^4{y}^7}$