Which algebraic expression represents the phrase "the quotient of negative eight and the sum of a number and three"?

What is the length of the missing leg in this right triangle? 18 mm 24 mm 26 mm 32 mm

Any is very appreciated! (picture is provided below)not sure how to do this at all won't lie

Aword processing program requires a 7- digit registration code made up of the digits 1,2,4,5,6,7 and 9 each number has to be used and no number can be used mor than once how many codes are possible