15!/10!5!
(3-3)!
10!/7!3!
(6-5)!
(3!)^2
8!4!/3!
20 is 66 23% of what number
the number 20 is 66 23% of what number
(x-1)(x+2)^2-(x-1)^2(x+2)
x+5y=25
Find the value of y
