Answer:
Step-by-step explanation:
An equation contains a sign equality (=) between two expressions.
And an expression is a simple algebraic statement.
By these definitions,
Equations Expressions
x = 2x + 5 21x - 13 + 11x
-3.7x - 13
3x + 1 = -2.1 
there isn’t an image provided I can’t help unless you give an image
C. It is always a rational number. You cannot determine its sign without knowing the values of a and b.