What is the branch of Mathematics in which letters and other general symbols are used to represent numbers and quantities in formulae and equations?

Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics with the major subdisciplines of number theory,[1] algebra,[2] geometry,[1] and analysis,[3] respectively. There is no general consensus among mathematicians about a common definition for their academic discipline.

A letter that stands for a number in an expression or an equation is called a

What do you call a correct arrangement of mathematical symbols that states a completethought?

Trigonometry is the branch of mathematics which deals with:

An __________ signifies a combination of numbers, variables, and operation symbols.