Yes it is a function because there are not any repeating x values ( first number in each set of parentheses)
108x/56x Hope that helps.
To get from 40% to 100%, divide by 2 and multiply by 5.
I.e. 40/2 = 20
20 x 5 = 100%
Do the exact same for 102
102/2 = 51
51 x 5 = 255 students
A3^2+4=1604
a3=40
a2^2+4=40
a2=6
a1^2+4=6
a1=√2
So the first two terms are √2 and 6, answer C