But since we are multiplying an inequality by a negative number you have to swap the inequality sign.

但是由于我们将不等式乘以负数，因此您必须交换不等号。

We're going to have to swap this inequality sign as well, and this positive 2.13 will become a negative 2.13.

我们还必须交换这个不等号，这个正数 2.13 将变成负数 2.13。