Help solve this word problem

Question

The science fair projects are set up on tables. There are 99 long tables used. Each long table holds 7 projects. The rest of the projects are set up on short tables. Each short table can hold 4 projects. What is the fewest number of short tables that will be needed for the rest of the projects?

 

The chart shows  3 grade with 462 

                         4 grade with 759

                         5 grade with 891

Answer 1

The sum of all the projects from grades 3 - 5 is 2,112.  If 7 × 99 projects are placed on the long tables, hat leaves2112 - 693 = 1419 projects for short tables.  We divide 1419 projects by 4 projects/table and we get 354.75 tables, so there will have to be 355 short tables (the last one will only have 3 projects displayed on it).