The lantern theater found that 85% of last year's sold out plays occur during saturdays performances. based on this information the box office manager decided to add an additional perfomance time each saturday. this desicion is a result of

This desicion is a result of 85% increased sale of the plays during saturdays performances.

Step-by-step explanation:

The information given is a statistics of last year's plays sale. According to which,  85% sale was increased when the plays were performed on saturday. Therefore the sales and accounting department of production office has decided that they should add an additional performance time on Saturdays so they sale can be increased further.