In 2 years theirs 17520 in total!
By the binomial theorem,

where

Then the coefficients of the
terms in the expansion are, in order from
to
,





He spent $36 on safety equipment.
The total cost each time was $11, meaning he had to pay 9 times for each skate session. 4x9=36! ( 7x9= 63 so if you add 36 you'll get 99 just as a way of checking)
Do you watch/read pandora hearts?
24,610. All you have to do is multiply 5 and 4,852 and add 150.