Question

Use an alternative method to express the following set: {y:y is a person in your math class and also more than 100 years old.}

Answer 1

Let's use the letter M to label the math class. The fact that person y is in that class can be expressed by:

$y\in M$

We also have to show that is older than 100 so we have:

$y>100$

If we put all this information together we get:

$\mleft\lbrace y\colon y\in M,y>100\mright\rbrace$

And that's an alternative way to express the set.