How do i evaluate an expression with a given variable

To evaluate an expression with a given variable means to replace the number in the place of the variable, and then solve to find what the expression equals. 
Example would be: x + 3 and x = 4
x + 3
4+3 = 7
7 is the value of the expression now. 

Answercounterclockwise rotation about the origin by 180 degrees followed by reflection about the y-axisexplanationthe given figure has verticesrecall that for counterclockwise rotation about the origin, when we rotate figure pqrs counterclockwise through an angle of 180° about the origin, the coordinates will becomenext, we reflect in the y-axis by negating the x-coordinates of the resulting figure to obtain,therefore the correct answer is c