Sheila walked 7.7 km to the library, about how many miles did she walk? A.9
B.5
C.6
1D.2

HEL Plz

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

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 cost of using a service is $0.25 per min. what equation correctly represents the total cost c, in dollars, for d days of use?