What fraction is equivalent to 5/10

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?

In the diagram below,abc is congruent to dec what is the value of x

Write each rational number in the form a/b, where a and b are integers. 1. 5 1/6 2. -12