Astudent bought 84 pencils. if he sharpened 35 pencils, what is the ratio of the unsharpened pencils to the sharpened pencils?

Number of pencils bough by the student = 84
Number of pencils sharpened by the student = 35
Then
The number of pencils that was not sharpened = (84 - 35)
                                                                             = 49
So 35 pencils have been sharpened and 49 pencils have not been sharpened.
Then Number of pencils unsharpened:Number of pencils sharpened = 49:35
                                                                                                               = 7:5
So the ratio of the number of unsharpened pencil to the number of sharpened pencil is 7:5