Well u would multiply 20 x 15 to find out the highest if the range which is 300 . So that knocks it down to B or D. But since they're $15 each, It would be based of the multiples of 15 making your answer B .
The range is all the y values.....or the f(x) values .
So the practical range would be the multiples of 15 between 0 and 300,Inclusive .
