A. yes...the data is a function because for every x value, there is only one y value.
B. f(x) = 3x - 10...when x = 8
 f(8) = 3(8) - 10
 f(8) = 24 - 10
 f(8) = 14
 
 the table : wen x = 8, y = 4
 f(x) = 3x - 10 has a greater value
C. 80 = 3x - 10
 80 + 10 = 3x
 90 = 3x
 90/3 = x
 30 = x