Wow that looks a little difficult. good ouck!
It is 141.4 centimetres. This is because the circumference is obtained by multiplying pi with the diameter.
Depends if you want
1. find how much he will earn, find the differnce between that and 18000
2. see how much to invest till he will get 18000
A=

A=futre amount
P=present amout
r=rate in decimal
n=number of times per year ccompounded
t=time in years
1.
A=?
P=9000
r=0.06
n=4 (quarter means 4 times per year)
t=2
?=

?=

?=

?=10138.4 will be earned
18000-10138.4=7861.6 needed
2.
A=18000
P=9000+x
r=0.06
n=4 (quarter means 4 times per year)
t=2
18000=

18000=

18000=

divide both sides by 1.015^8
15978.8=9000+x
minus 9000 both sides
6978.8 needed
if he willnot be investing any more, he needs $7861.6 more
if he will invest more he will need to invest $6978.8 more
So five pages of her fiction book in 7 minutes. And she must read thirty pages:
30/5 = 6.
6 * 7 = 42 minutes for the fiction book.
So 2 pages of her history book in seven minutes.
30/2 = 15.
15 * 7 = 105 minutes for the history textbook
Add:
42 + 105 = 147 minutes.