Please help what is 30d2 -18d

You are designing a rectangular pet pen for your new baby puppy. you have 30 feet of fencing you would like the fencing to be 6 1/3 feet longer than the width

Of the 304 people who attended a school play, 5/8 were students. how many of the people who attended were students.

What multiplys to be 1 but adds up to be 4