Which of these describes the lithosphere and the asthenosphere? a the lithosphere is rigid and immovable, and the asthenosphere is hot and flowing. b the asthenosphere is rigid and immovable, and the lithosphere is hot and flowing. c both are hot inner layers of earth capable of bending and moving. d both are hard and rigid layers of earth close to the surface?

Amath expression is a collection of one or more terms, which are separated by the signs ( + , - , x , / ).example :   8+b8+b  or  a−3a−3in algebra, an equation is a mathematical statement with two expressions where, each expression is separated by an equal (=) sign. variables can be present on both the sides of the equality (=) sign and we use letters to denote such variables.example 1:   x=4+2x=4+2  , [here, we can observe that the variable is present only on one side of the equation].example 2:   2x+3=x+42x+3=x+4  , [here, we can observe that the variables are present on both side of the equation].

The answer would be  b. hope this !