What is the significance of hadrian's wall?
a. the wall has a monument to fallen roman soldiers
b. the wall marked the boundary between acient greece and rome
c. the wall was built as a temporary structure but lasted hundreds of years
d. the wall marked the northern defensive boundary of roman britain

The answer is D.)the wall marked the northern defensive boundary of Roman Britain.

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].

Answergoogle earth; i believe this is the correct answer, plz check first;