Sarah want to 1 mile from her home to her school and 625 feet from her school to the library if she follow the same path to go back from the library to her home how far did she walk altogether

Can someone me do math because i am having a breakdown rn because i don’t get it

Asystem of equations has 1 solution.if 4x-y=5 is one of the equations , which could be the other equation ?

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?