Billy was counting the number of wheels and bike seats at the playground. he saw tricycles and bicycles. he counted 79 wheels and 28 seats. how many bicycles did billy see?

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?

Solve each quadratic equation by factoring and using the zero product property. x^2 + 18x = 9x

*segment an is an altitude of right ? abc with a right angle at a. if ab = 2root 5 in and nc = 1 in, find bn, an, ac.