How would you write this number in numeric form eight hundred fifty-three hundredths?

Mindy bought 5/8 pound of almonds and a 3/4 pound of walnuts. which pair of fraction cannot be used to find how many pounds of nuts she bought in all.

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?

Ijust need these 2 questions answered (the second pic is just confirmation i'm not confident in that answer)