Physical science : find the speed of an object that covers 400 km in 5 hr.
a. 40 km/hr
b. 80 km/hr
c. 2000 km/hr
d. 800 km/hr

In the pendulum formula t=2pi. read the problem on the picture ! ; $; $; ! ; ! ; ! ; )$; ! ; ! ; ! ; $; $; $! ; ! ; ); $; $$

What is the slope of the line that contains the points (-2,1) and (0,-3)

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?