Please tell me your opinions, each of you.

He is good at explaining that theory.

He was able to solve the complex calculation quickly.

He was calculating in his head.

The theory of directed graphs is a branch of mathematics.

This bar graph shows the sales of each product.

Graph theory is a branch of mathematics that studies the structure of networks.

It is important to understand the importance of health.

An undirected graph is a type of graph where the direction of the edges is not specified.

I commute by local train.