Can someone help me
im at 99 percent on khan and i have the final skill at level one but i just can't get the mastery challege

What is the radical expression that is equivalent to the expression 27 1 over 5?

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 domain of a function can be represented by which one of the following options? o a. a set of output values o b. a set of f(x) values o c. a set of input values o d. a set of both input and output values