Mrs. grijalva hired a landscaping company to landscape her back yard. the company has a standing policy to plant 3 bushes for every tree planted. the company charges $75 for each tree planted and $20 for each bush. mrs. grijalva was billed for $810 after the planting was complete. how many bushes did the company plant in mrs. grijalva’s back yard?
a.
2
b.
6
c.
18
d.
54

Each person in an it department of 25 people works on at least one of 3 major projects: system security, program implementation, platform development. 10 people work on system security, 13 work on program implementation, and 12 work on platform development. 4 people work on system security and platform development, 5 people work on program implementation and platform development, and 2 people work on all three projects. how many people work on system security and program implementation?