There are 20 birds in a tree. 10 are blue birds, 5 are robins and 5 are crows. What percent of the birds are blue birds?

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?

What is the sum of these mixed numbers 4 2/3+ 3 1/9

Parallelogram efgh is a rectangle. he = 6, and fe = 8. find ge: and find fj: