math mode - How to get big curly braces for an equation with 3 parts? - TeX - LaTeX Stack Exchange

I am very new to LaTeX. I want to display this: How should I go about doing this?

Double subscript - Overleaf, Online LaTeX Editor

Equations - How To Scale Eqnarray To Fit Page Width - TeX - LaTeX Stack Exchange, PDF, Te X

MathJax basic tutorial and quick reference - PhysicsOverflow

Hands-on Math K-12 - Flipbook by sherman

LaTeX glossary and list of acronyms – texblog

Client Resources

Help Online - User Guide - Customizing Graphs

Writing Math Equations in Jupyter Notebook: A Naive Introduction, by Abhay Shukla, Analytics Vidhya

Use GNU Emacs

latex - Two statements next to curly brace in an equation - Stack Overflow