Help needed, much appreciated

Which elements in the set below are integers? 12, –3⁄4,√ 25 , –7, √ 5 , 14⁄7, 9 a. 12, √ 25 , –7, 9 b. 12, √ 25 , –7, 14⁄7, 9 c. –3⁄4, 25 , √ 5 ,14⁄7 d. 12, –7, 9

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?

The sum of 5consecutive even numbers is 100. what is the first number in this sequence?