A 12 inch object is placed 30 inches in front of a plane mirror

Ineed ! i have no clue how to do this problem.

To calculate percent by mass, use the equation below: calculate the percent by mass of each element. %n = % %h = % %o = %

The activation energy for the reaction no2(g)+co2(g)⟶no(g)+co(g) is ea = 300 kj/mol and the change in enthalpy for the reaction is δh = -100 kj/mol . what is the activation energy for the reverse reaction?