Sergio has 79 paintings in his art collection. He and other local painting collectors agreed to donate some paintings to the local museum. Each of the collectors will donate the same number of paintings, and the total number of paintings donated by the collectors will be 48. How many paintings will Sergio have in his art collection after his donation?

Regretfully, I think we should be given the number of other local painting collectors (apart from Sergio) in order to answer this question. However, if we let x be the number of local painting collectors then, there are x + 1 painting collectors all in all. Each of the collector will then have to donate 48 / (x+1) each. Subtracting this value from the total number of paintings that Sergio initially has, our final answer would be,

79 - 48 / (x+1)