Question

Mike scored 6000 points in game. In the next five rounds he was out of form and hence, could make only a total of 90 points, as a result of which his average fell by 2 points. How many rounds did he play in all?

Answer 1

I am adding the steps to arrive at the solution.
 (May be helpful for some others who wish to know.)

Assume the innings as X and Average as Y.Form equations with the formula for average=runs/Innings.The equations will be, 
Y=6000/X and  (Y-2)=6090/(X+5).Solving the above two equations, the values of X and Y will be 100 & 60.So the total innings played will be X+5 which will be equal to 105