If you place a small needle between the north poles of two bar magnets, will the needle become magnetized

the old price per ounce is c/4.

the new price per ounce is c/3.6.

the ratio of the old price to the new one is

(c/4)/(c/3.6) = (c/c)×(3.6/4) = 0.9 . . = 9/10 . . "nine tenths" in either form

i would say

54 degrees incident angle = reflected angle

angle is from normal turned to line of ray