You are given a math word problem and you are supposed to apply multiple mathematical operators like addition, subtraction, multiplication, or division on the numbers embedded in the text to answer the following question and then only report the final numerical answer.
--------
Question: katie spent a total $ 350 on her whole stay in the island . if she spent $ 125 on food and $ 135 on hotel rooms how much did she spend on buying other stuff ?

Answer: 90

Question: a company invited 68 people to a luncheon but 50 of them did n't show up . if the tables they had held 3 people each how many tables do they need ?

Answer: 6

Question: professor treehead of the flora university requested his students to participate . he said that they planted 15 species of trees in the natural park 20 species of trees in the neighboring forest and 10 species of trees all around different locations in town . how many species of trees were planted by the students ?

Answer:
45