Literal equation:
we know that
literal equation is equation of more one variable
for example: [tex] 2x+3y=1 [/tex]
And we can solve such equations only if we are given two such equation
because it has two variables
One variable equation:
such equation has single variables
for example:
[tex] 3x=21 [/tex]
we don't need any other equation
we can solve for variables from single equation itself
because it has only one variable that is x