in an_______expression, any letter or symbol that represent a number is called a_________.A specific number. or a fixed value is called a_________.A____________is a number or variable to a product or quotient of variable and terms are separated by plus (+)or minus (-) sign.It is not necessary to write the +sign up the beginning of the term but it is a must to write the -sign before a term if it is in front of the term in an expression.Thethe numerical factor of the term that contains variable is called numerical __________.​