1. let l be the length of the rectangle and let w be the width.

then, by your question:

so the perimeler is given by :

since perimeter = 42, you have so,

then

so l=13 and w = 8

2. if x is the first integer, then and are the two consecutive integers after x. the question is saying that

3. you can factorize as so one of your factors is ...