1, 5, 14, 30, 50, 55, 91?.

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 triangle △abc, ∠abc=90°, bh is an altitude. find the missing lengths. ah=4 and hc=1, find bh.

The pair of coordinates that do not represent the point( 5,150’) is a. (5,-210) b. (5,210) c. (-5,330) d. (-5,-30)