Six less than a number w squared

Acredit card advertises an annual interest rate of 23%. what is the equivalent monthly interest rate?

The square pyramid has a volume of 441 cubic inches. what is the value of x? 1/7x is the height x is the base

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?